Release 0.11.0.0

singleFieldSubscriptionsRule picks up a wrong fragment definition.

.gitignore

@@ -8,7 +8,8 @@
 .cabal-sandbox/
 cabal.sandbox.config
 cabal.project.local
-/graphql.cabal
 
 # GHC
 *.hi
+*.o
+/docs/tutorial/tutorial

CHANGELOG.md

@@ -6,7 +6,192 @@ The format is based on
 and this project adheres to
 [Haskell Package Versioning Policy](https://pvp.haskell.org/).
 
-## [Unreleased]
+## [0.11.0.0] - 2020-11-07
+### Changed
+- `AST.Document.Selection` wraps additional new types: `Field`, `FragmentSpread`
+  and  `InlineFragment`. Thus validation rules can be defined more concise.
+- `AST.Document`: `Argument` and `Directive` contain token location.
+- `AST.Document.Argument` contains the `Value` wrapped in the `Node`.
+- `AST.Lexer.colon` and `AST.Lexer.at` ignore the result (it is always the
+- same).
+- `Validate.Validation`: `Validation.rules` was removed. `Validation.rules`
+  contained the list of rules, but the executed rules shouldn't know about other
+  rules. `rules` was a part of the `Validation` context to pass it easier
+  around, but since the rules are traversed once now and applied to all nodes in
+  the tree at the beginning, it isn't required anymore.
+- `Validate.Validation.Error`: `path` is removed since it isn't possible to get
+  the path without executing the query.
+- `Error.Error`: `path` added. It is currently always empty.
+- `Validate.Validation.Path` was moved to `Error`.
+- `Type.Schema.Schema`: data constructor is hidden, fields are accessible with
+  freestanding functions: `query`, `mutation`, `subscription`, `directives` and
+  `types`.
+
+### Added
+- `Validate.Validation.Rule` constructors:
+  - `SelectionRule`
+  - `FragmentRule`
+  - `FragmentSpreadRule`
+  - `ArgumentsRule`
+  - `DirectivesRule`
+  - `VariablesRule`
+  - `FieldRule`
+- `Validate.Rules`:
+  - `fragmentsOnCompositeTypesRule`
+  - `fragmentSpreadTargetDefinedRule`
+  - `fragmentSpreadTypeExistenceRule`
+  - `noUnusedFragmentsRule`
+  - `noFragmentCyclesRule`
+  - `uniqueArgumentNamesRule`
+  - `uniqueDirectiveNamesRule`
+  - `uniqueVariableNamesRule`
+  - `variablesAreInputTypesRule`
+  - `noUndefinedVariablesRule`
+  - `noUndefinedVariablesRule`
+  - `noUnusedVariablesRule`
+  - `uniqueInputFieldNamesRule`
+  - `fieldsOnCorrectTypeRule`
+  - `scalarLeafsRule`
+  - `knownArgumentNamesRule`
+  - `knownDirectiveNamesRule`
+  - `directivesInValidLocationsRule`
+  - `providedRequiredArgumentsRule`
+  - `providedRequiredInputFieldsRule`
+- `AST.Document.Field`.
+- `AST.Document.FragmentSpread`.
+- `AST.Document.InlineFragment`.
+- `AST.Document.Node`.
+- `Type.In.Arguments`: Type alias for an argument map.
+- `Type.Schema.Directive` and `Type.Schema.Directives` are directive definition
+  representation.
+- `Type.Schema.schema`: Schema constructor.
+
+### Fixed
+- Collecting existing types from the schema considers subscriptions.
+
+### Removed
+- `AST.Document.Alias`. Use `AST.Document.Name` instead.
+
+## [0.10.0.0] - 2020-08-29
+### Changed
+- `Test.Hspec.GraphQL.*`: replace `IO` in the resolver with any `MonadCatch`.
+- The `Location` argument of `AST.Document.Definition.ExecutableDefinition` was
+  moved to `OperationDefinition` and `FragmentDefinition` since these are the
+  actual elements that have a location in the document.
+- `Validate.Rules` get the whole validation context (AST and schema).
+
+### Added
+- `Validate.Validation` contains data structures and functions used by the
+  validator and concretet rules.
+- `Validate.Rules`: operation validation rules.
+
+## [0.9.0.0] - 2020-07-24
+### Fixed
+- Location of a parse error is returned in a singleton array with key
+  `locations`.
+- Parsing comments in the front of definitions.
+- Some missing labels were added to the parsers, some labels were fixed to
+  refer to the AST nodes being parsed. 
+
+### Added
+- `AST` reexports `AST.Parser`.
+- `AST.Document.Location` is a token location as a line and column pair.
+- `Execute` reexports `Execute.Coerce`.
+- `Error.Error` is an error representation with a message and source location.
+- `Error.Response` represents a result of running a GraphQL query.
+- `Type.Schema` exports `Type` which lists all types possible in the schema.
+- Parsing subscriptions.
+- `Error.ResponseEventStream`, `Type.Out.Resolve`, `Type.Out.Subscribe` and
+  `Type.Out.SourceEventStream` define subscription resolvers.
+- `Error.ResolverException` is an exception that can be thrown by (field value
+  and event stream) resolvers to signalize an error. Other exceptions will
+  escape.
+- `Test.Hspec.GraphQL` contains some test helpers.
+- `Validate` contains the validator and standard rules.
+
+### Changed
+- `Type.Out.Resolver`: Interface fields don't have resolvers, object fields
+  have value resolvers, root subscription type resolvers need an additional
+  resolver that creates an event stream. `Resolver` represents these differences
+  now and pairs a field with the function(s). Resolvers don't have `ExceptT`,
+  errors are handled with `MonadThrow`/`MonadCatch`.
+- All code from `Trans` is moved to `Type.Out` and exported by `Type` and
+  `Type.Out`.
+- `AST.Core` contained only `Arguments` which was moved to `Type.Definition`.
+  `AST` provides now only functionality related to parsing and encoding, as it
+  should be.
+- `Execute.execute` takes an additional argument, a possible operation name
+  and returns either a stream or the response.
+- `Error` module was changed to work with dedicated types for errors and the
+  response instead of JSON.
+- `graphqlSubs` takes an additional argument, the operation name. The type of
+  variable names is changed back to JSON since it is a common format and it
+  saves additional conversions. Custom format still can be used with the
+  underlying functions (in the `Execute` module). The function returns either a
+  a stream or the resolved value.
+- `graphql` returns either a stream or the resolved value.
+- The constraint of the base monad was changed to `MonadCatch` (and it implies
+  `MonadThrow`).
+
+### Removed
+- `Trans.ActionT` is an unneeded layer of complexity. `Type.Out.Resolver`
+  represents possible resolver configurations.
+- `Execute.executeWithName`. `Execute.execute` takes the operation name and
+   completely replaces `executeWithName`.
+
+## [0.8.0.0] - 2020-06-20
+### Fixed
+- The parser rejects variables when parsing defaultValue (DefaultValue). The
+  specification defines default values as `Value` with `const` parameter and
+  constants cannot be variables. `AST.Document.ConstValue` was added,
+  `AST.Document.ObjectField` was modified.
+- AST transformation should never fail.
+    * Arguments and fields with a missing variable as value should be left out.
+    * Invalid (recusrive or non-existing) fragments should be skipped.
+- Argument value coercion.
+- Variable value coercion.
+- Result coercion.
+- The executor should skip the fields missing in the object type and not fail.
+- Merging subselections.
+
+### Changed
+- `Schema.Resolver` was moved to `Type.Out`, it is a field and resolver function
+  pair.
+- `AST.Core.Value` was moved into `Type.Definition`. These values are used only
+  in the execution and type system, it is not a part of the parsing tree.
+- `Type` module is superseded by `Type.Out`. This module contains now only
+  exports from other module that complete `Type.In` and `Type.Out` exports.
+- `Error.CollectErrsT` contains the new `Resolution` data structure.
+  `Resolution` represents the state used by the executor. It contains all types
+  defined in the schema and collects the thrown errors.
+
+### Added
+- `Type.Definition` contains base type system definition, e.g. Enums and
+  Scalars.
+- `Type.Schema` describes a schema. Both public functions that execute queries
+  accept a `Schema` now instead of a `HashMap`. The execution fails if the root
+  operation doesn't match the root Query type in the schema.
+- `Type.In` and `Type.Out` contain definitions for input and output types.
+- `Execute.Coerce` defines a typeclass responsible for input, variable value
+  coercion. It decouples us a bit from JSON since any format can be used to pass
+  query variables. Execution functions accept (`HashMap Name a`) instead of
+  `Subs`, where a is an instance of `VariableValue`.
+
+### Removed
+- `Schema.scalar`, `Schema.wrappedScalar`. They accepted everything can be
+  converted to JSON and JSON is not suitable as an internal representation for
+  GraphQL. E.g. GraphQL distinguishes between Floats and Integers.
+- `Schema.wrappedObject`, `Schema.object`, `Schema.resolversToMap`. There is no
+  need in special functions to construct field resolvers anymore, resolvers are
+  normal functions attached to the fields in the schema representation.
+- `Schema.resolve` is superseded by `Execute.Execution`.
+- `Error.runAppendErrs` isn't used anywhere.
+- `AST.Core`: `Document`, `Directive`, `Field`, `Fragment`, `Selection`, `Alias`
+  `TypeCondition` were modified, moved into `Execute.Transform.Document` and
+  made private. These types describe intermediate representation used by the
+  executor internally. Moving was required to avoid cyclic dependencies between
+  the executor and type system.
+- `AST.Core` doesn't reexports anything.
 
 ## [0.7.0.0] - 2020-05-11
 ### Fixed
@@ -20,7 +205,7 @@ and this project adheres to
 - `Trans.argument`.
 - Schema extension parser.
 - Contributing guidelines.
-- `Schema.resolversToMap` (intended for to be used internally).
+- `Schema.resolversToMap` (intended to be used internally).
 
 ### Changed
 - Rename `AST.Definition` into `AST.Document.ExecutableDefinition`.
@@ -215,14 +400,17 @@ and this project adheres to
 ### Added
 - Data types for the GraphQL language.
 
-[Unreleased]: https://github.com/caraus-ecms/graphql/compare/v0.6.1.0...HEAD
-[0.7.0.0]: https://github.com/caraus-ecms/graphql/compare/v0.6.1.0...v0.7.0.0
-[0.6.1.0]: https://github.com/caraus-ecms/graphql/compare/v0.6.0.0...v0.6.1.0
-[0.6.0.0]: https://github.com/caraus-ecms/graphql/compare/v0.5.1.0...v0.6.0.0
-[0.5.1.0]: https://github.com/caraus-ecms/graphql/compare/v0.5.0.1...v0.5.1.0
-[0.5.0.1]: https://github.com/caraus-ecms/graphql/compare/v0.5.0.0...v0.5.0.1
-[0.5.0.0]: https://github.com/caraus-ecms/graphql/compare/v0.4.0.0...v0.5.0.0
-[0.4.0.0]: https://github.com/caraus-ecms/graphql/compare/v0.3...v0.4.0.0
-[0.3]: https://github.com/caraus-ecms/graphql/compare/v0.2.1...v0.3
-[0.2.1]: https://github.com/caraus-ecms/graphql/compare/v0.2...v0.2.1
-[0.2]: https://github.com/caraus-ecms/graphql/compare/v0.1...v0.2
+[0.11.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.11.0.0&rev_to=v0.10.0.0
+[0.10.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.10.0.0&rev_to=v0.9.0.0
+[0.9.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.9.0.0&rev_to=v0.8.0.0
+[0.8.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.8.0.0&rev_to=v0.7.0.0
+[0.7.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.7.0.0&rev_to=v0.6.1.0
+[0.6.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.6.1.0&rev_to=v0.6.0.0
+[0.6.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.6.0.0&rev_to=v0.5.1.0
+[0.5.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.5.1.0&rev_to=v0.5.0.1
+[0.5.0.1]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.5.0.1&rev_to=v0.5.0.0
+[0.5.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.5.0.0&rev_to=v0.4.0.0
+[0.4.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.4.0.0&rev_to=v0.3
+[0.3]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.3&rev_to=v0.2.1
+[0.2.1]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.2.1&rev_to=v0.2
+[0.2]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.2&rev_to=v0.1

CONTRIBUTING.md

@@ -1,31 +0,0 @@
-# Contributing guidelines
-
-## Testing
-
-To ensure all code changes adhere to existing code quality standards, some
-automatic checks can be run locally.
-
-Ensure that the code builds without warnings and passes the tests:
-
-```sh
-stack test --pedantic
-```
-
-And also run the linter on your code:
-
-```sh
-stack build hlint
-stack exec hlint -- src tests
-```
-
-Build the documentation and check if you get any warnings:
-
-```sh
-stack haddock
-```
-
-Validate that literate Haskell (tutorials) files compile without any warnings:
-
-```sh
-stack ghc -- -Wall -fno-code docs/tutorial/*.lhs
-```

LICENSE.MPL

@@ -0,0 +1,373 @@
+Mozilla Public License Version 2.0
+==================================
+
+1. Definitions
+--------------
+
+1.1. "Contributor"
+    means each individual or legal entity that creates, contributes to
+    the creation of, or owns Covered Software.
+
+1.2. "Contributor Version"
+    means the combination of the Contributions of others (if any) used
+    by a Contributor and that particular Contributor's Contribution.
+
+1.3. "Contribution"
+    means Covered Software of a particular Contributor.
+
+1.4. "Covered Software"
+    means Source Code Form to which the initial Contributor has attached
+    the notice in Exhibit A, the Executable Form of such Source Code
+    Form, and Modifications of such Source Code Form, in each case
+    including portions thereof.
+
+1.5. "Incompatible With Secondary Licenses"
+    means
+
+    (a) that the initial Contributor has attached the notice described
+        in Exhibit B to the Covered Software; or
+
+    (b) that the Covered Software was made available under the terms of
+        version 1.1 or earlier of the License, but not also under the
+        terms of a Secondary License.
+
+1.6. "Executable Form"
+    means any form of the work other than Source Code Form.
+
+1.7. "Larger Work"
+    means a work that combines Covered Software with other material, in
+    a separate file or files, that is not Covered Software.
+
+1.8. "License"
+    means this document.
+
+1.9. "Licensable"
+    means having the right to grant, to the maximum extent possible,
+    whether at the time of the initial grant or subsequently, any and
+    all of the rights conveyed by this License.
+
+1.10. "Modifications"
+    means any of the following:
+
+    (a) any file in Source Code Form that results from an addition to,
+        deletion from, or modification of the contents of Covered
+        Software; or
+
+    (b) any new file in Source Code Form that contains any Covered
+        Software.
+
+1.11. "Patent Claims" of a Contributor
+    means any patent claim(s), including without limitation, method,
+    process, and apparatus claims, in any patent Licensable by such
+    Contributor that would be infringed, but for the grant of the
+    License, by the making, using, selling, offering for sale, having
+    made, import, or transfer of either its Contributions or its
+    Contributor Version.
+
+1.12. "Secondary License"
+    means either the GNU General Public License, Version 2.0, the GNU
+    Lesser General Public License, Version 2.1, the GNU Affero General
+    Public License, Version 3.0, or any later versions of those
+    licenses.
+
+1.13. "Source Code Form"
+    means the form of the work preferred for making modifications.
+
+1.14. "You" (or "Your")
+    means an individual or a legal entity exercising rights under this
+    License. For legal entities, "You" includes any entity that
+    controls, is controlled by, or is under common control with You. For
+    purposes of this definition, "control" means (a) the power, direct
+    or indirect, to cause the direction or management of such entity,
+    whether by contract or otherwise, or (b) ownership of more than
+    fifty percent (50%) of the outstanding shares or beneficial
+    ownership of such entity.
+
+2. License Grants and Conditions
+--------------------------------
+
+2.1. Grants
+
+Each Contributor hereby grants You a world-wide, royalty-free,
+non-exclusive license:
+
+(a) under intellectual property rights (other than patent or trademark)
+    Licensable by such Contributor to use, reproduce, make available,
+    modify, display, perform, distribute, and otherwise exploit its
+    Contributions, either on an unmodified basis, with Modifications, or
+    as part of a Larger Work; and
+
+(b) under Patent Claims of such Contributor to make, use, sell, offer
+    for sale, have made, import, and otherwise transfer either its
+    Contributions or its Contributor Version.
+
+2.2. Effective Date
+
+The licenses granted in Section 2.1 with respect to any Contribution
+become effective for each Contribution on the date the Contributor first
+distributes such Contribution.
+
+2.3. Limitations on Grant Scope
+
+The licenses granted in this Section 2 are the only rights granted under
+this License. No additional rights or licenses will be implied from the
+distribution or licensing of Covered Software under this License.
+Notwithstanding Section 2.1(b) above, no patent license is granted by a
+Contributor:
+
+(a) for any code that a Contributor has removed from Covered Software;
+    or
+
+(b) for infringements caused by: (i) Your and any other third party's
+    modifications of Covered Software, or (ii) the combination of its
+    Contributions with other software (except as part of its Contributor
+    Version); or
+
+(c) under Patent Claims infringed by Covered Software in the absence of
+    its Contributions.
+
+This License does not grant any rights in the trademarks, service marks,
+or logos of any Contributor (except as may be necessary to comply with
+the notice requirements in Section 3.4).
+
+2.4. Subsequent Licenses
+
+No Contributor makes additional grants as a result of Your choice to
+distribute the Covered Software under a subsequent version of this
+License (see Section 10.2) or under the terms of a Secondary License (if
+permitted under the terms of Section 3.3).
+
+2.5. Representation
+
+Each Contributor represents that the Contributor believes its
+Contributions are its original creation(s) or it has sufficient rights
+to grant the rights to its Contributions conveyed by this License.
+
+2.6. Fair Use
+
+This License is not intended to limit any rights You have under
+applicable copyright doctrines of fair use, fair dealing, or other
+equivalents.
+
+2.7. Conditions
+
+Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
+in Section 2.1.
+
+3. Responsibilities
+-------------------
+
+3.1. Distribution of Source Form
+
+All distribution of Covered Software in Source Code Form, including any
+Modifications that You create or to which You contribute, must be under
+the terms of this License. You must inform recipients that the Source
+Code Form of the Covered Software is governed by the terms of this
+License, and how they can obtain a copy of this License. You may not
+attempt to alter or restrict the recipients' rights in the Source Code
+Form.
+
+3.2. Distribution of Executable Form
+
+If You distribute Covered Software in Executable Form then:
+
+(a) such Covered Software must also be made available in Source Code
+    Form, as described in Section 3.1, and You must inform recipients of
+    the Executable Form how they can obtain a copy of such Source Code
+    Form by reasonable means in a timely manner, at a charge no more
+    than the cost of distribution to the recipient; and
+
+(b) You may distribute such Executable Form under the terms of this
+    License, or sublicense it under different terms, provided that the
+    license for the Executable Form does not attempt to limit or alter
+    the recipients' rights in the Source Code Form under this License.
+
+3.3. Distribution of a Larger Work
+
+You may create and distribute a Larger Work under terms of Your choice,
+provided that You also comply with the requirements of this License for
+the Covered Software. If the Larger Work is a combination of Covered
+Software with a work governed by one or more Secondary Licenses, and the
+Covered Software is not Incompatible With Secondary Licenses, this
+License permits You to additionally distribute such Covered Software
+under the terms of such Secondary License(s), so that the recipient of
+the Larger Work may, at their option, further distribute the Covered
+Software under the terms of either this License or such Secondary
+License(s).
+
+3.4. Notices
+
+You may not remove or alter the substance of any license notices
+(including copyright notices, patent notices, disclaimers of warranty,
+or limitations of liability) contained within the Source Code Form of
+the Covered Software, except that You may alter any license notices to
+the extent required to remedy known factual inaccuracies.
+
+3.5. Application of Additional Terms
+
+You may choose to offer, and to charge a fee for, warranty, support,
+indemnity or liability obligations to one or more recipients of Covered
+Software. However, You may do so only on Your own behalf, and not on
+behalf of any Contributor. You must make it absolutely clear that any
+such warranty, support, indemnity, or liability obligation is offered by
+You alone, and You hereby agree to indemnify every Contributor for any
+liability incurred by such Contributor as a result of warranty, support,
+indemnity or liability terms You offer. You may include additional
+disclaimers of warranty and limitations of liability specific to any
+jurisdiction.
+
+4. Inability to Comply Due to Statute or Regulation
+---------------------------------------------------
+
+If it is impossible for You to comply with any of the terms of this
+License with respect to some or all of the Covered Software due to
+statute, judicial order, or regulation then You must: (a) comply with
+the terms of this License to the maximum extent possible; and (b)
+describe the limitations and the code they affect. Such description must
+be placed in a text file included with all distributions of the Covered
+Software under this License. Except to the extent prohibited by statute
+or regulation, such description must be sufficiently detailed for a
+recipient of ordinary skill to be able to understand it.
+
+5. Termination
+--------------
+
+5.1. The rights granted under this License will terminate automatically
+if You fail to comply with any of its terms. However, if You become
+compliant, then the rights granted under this License from a particular
+Contributor are reinstated (a) provisionally, unless and until such
+Contributor explicitly and finally terminates Your grants, and (b) on an
+ongoing basis, if such Contributor fails to notify You of the
+non-compliance by some reasonable means prior to 60 days after You have
+come back into compliance. Moreover, Your grants from a particular
+Contributor are reinstated on an ongoing basis if such Contributor
+notifies You of the non-compliance by some reasonable means, this is the
+first time You have received notice of non-compliance with this License
+from such Contributor, and You become compliant prior to 30 days after
+Your receipt of the notice.
+
+5.2. If You initiate litigation against any entity by asserting a patent
+infringement claim (excluding declaratory judgment actions,
+counter-claims, and cross-claims) alleging that a Contributor Version
+directly or indirectly infringes any patent, then the rights granted to
+You by any and all Contributors for the Covered Software under Section
+2.1 of this License shall terminate.
+
+5.3. In the event of termination under Sections 5.1 or 5.2 above, all
+end user license agreements (excluding distributors and resellers) which
+have been validly granted by You or Your distributors under this License
+prior to termination shall survive termination.
+
+************************************************************************
+*                                                                      *
+*  6. Disclaimer of Warranty                                           *
+*  -------------------------                                           *
+*                                                                      *
+*  Covered Software is provided under this License on an "as is"       *
+*  basis, without warranty of any kind, either expressed, implied, or  *
+*  statutory, including, without limitation, warranties that the       *
+*  Covered Software is free of defects, merchantable, fit for a        *
+*  particular purpose or non-infringing. The entire risk as to the     *
+*  quality and performance of the Covered Software is with You.        *
+*  Should any Covered Software prove defective in any respect, You     *
+*  (not any Contributor) assume the cost of any necessary servicing,   *
+*  repair, or correction. This disclaimer of warranty constitutes an   *
+*  essential part of this License. No use of any Covered Software is   *
+*  authorized under this License except under this disclaimer.         *
+*                                                                      *
+************************************************************************
+
+************************************************************************
+*                                                                      *
+*  7. Limitation of Liability                                          *
+*  --------------------------                                          *
+*                                                                      *
+*  Under no circumstances and under no legal theory, whether tort      *
+*  (including negligence), contract, or otherwise, shall any           *
+*  Contributor, or anyone who distributes Covered Software as          *
+*  permitted above, be liable to You for any direct, indirect,         *
+*  special, incidental, or consequential damages of any character      *
+*  including, without limitation, damages for lost profits, loss of    *
+*  goodwill, work stoppage, computer failure or malfunction, or any    *
+*  and all other commercial damages or losses, even if such party      *
+*  shall have been informed of the possibility of such damages. This   *
+*  limitation of liability shall not apply to liability for death or   *
+*  personal injury resulting from such party's negligence to the       *
+*  extent applicable law prohibits such limitation. Some               *
+*  jurisdictions do not allow the exclusion or limitation of           *
+*  incidental or consequential damages, so this exclusion and          *
+*  limitation may not apply to You.                                    *
+*                                                                      *
+************************************************************************
+
+8. Litigation
+-------------
+
+Any litigation relating to this License may be brought only in the
+courts of a jurisdiction where the defendant maintains its principal
+place of business and such litigation shall be governed by laws of that
+jurisdiction, without reference to its conflict-of-law provisions.
+Nothing in this Section shall prevent a party's ability to bring
+cross-claims or counter-claims.
+
+9. Miscellaneous
+----------------
+
+This License represents the complete agreement concerning the subject
+matter hereof. If any provision of this License is held to be
+unenforceable, such provision shall be reformed only to the extent
+necessary to make it enforceable. Any law or regulation which provides
+that the language of a contract shall be construed against the drafter
+shall not be used to construe this License against a Contributor.
+
+10. Versions of the License
+---------------------------
+
+10.1. New Versions
+
+Mozilla Foundation is the license steward. Except as provided in Section
+10.3, no one other than the license steward has the right to modify or
+publish new versions of this License. Each version will be given a
+distinguishing version number.
+
+10.2. Effect of New Versions
+
+You may distribute the Covered Software under the terms of the version
+of the License under which You originally received the Covered Software,
+or under the terms of any subsequent version published by the license
+steward.
+
+10.3. Modified Versions
+
+If you create software not governed by this License, and you want to
+create a new license for such software, you may create and use a
+modified version of this License if you rename the license and remove
+any references to the name of the license steward (except to note that
+such modified license differs from this License).
+
+10.4. Distributing Source Code Form that is Incompatible With Secondary
+Licenses
+
+If You choose to distribute Source Code Form that is Incompatible With
+Secondary Licenses under the terms of this version of the License, the
+notice described in Exhibit B of this License must be attached.
+
+Exhibit A - Source Code Form License Notice
+-------------------------------------------
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.
+
+You may add additional accurate notices of copyright ownership.
+
+Exhibit B - "Incompatible With Secondary Licenses" Notice
+---------------------------------------------------------
+
+  This Source Code Form is "Incompatible With Secondary Licenses", as
+  defined by the Mozilla Public License, v. 2.0.

README.md

@@ -1,10 +1,7 @@
-# Haskell GraphQL
+# GraphQL implementation in Haskell
 
-[![Hackage Version](https://img.shields.io/hackage/v/graphql.svg)](https://hackage.haskell.org/package/graphql)
-[![Build Status](https://semaphoreci.com/api/v1/belka-ew/graphql/branches/master/badge.svg)](https://semaphoreci.com/belka-ew/graphql)
-[![License](https://img.shields.io/badge/license-BSD--3--Clause-blue.svg)](https://raw.githubusercontent.com/caraus-ecms/graphql/master/LICENSE)
-
-GraphQL implementation in Haskell.
+[![Simple Haskell](https://www.simplehaskell.org/badges/badge.svg)](https://www.simplehaskell.org)
+[![CI/CD](https://img.shields.io/badge/CI-CD-brightgreen)](https://build.caraus.tech/go/pipelines)
 
 This implementation is relatively low-level by design, it doesn't provide any
 mappings between the GraphQL types and Haskell's type system and avoids
@@ -13,36 +10,25 @@ be built on top of it.
 
 ## State of the work
 
-For now this only provides a parser and a printer for the GraphQL query
-language and allows to execute queries and mutations without the schema
-validation step. But the idea is to be a Haskell port of
+For now this library provides:
+
+- Parser for the query and schema languages, as well as a printer for the query
+  language (minimizer and pretty-printer).
+- Data structures to define a type system.
+- Executor (queries, mutations and subscriptions are supported).
+- Validation is work in progress.
+- Introspection isn't available yet.
+
+But the idea is to be a Haskell port of
 [`graphql-js`](https://github.com/graphql/graphql-js).
 
-For the list of currently missing features see issues marked as
-"[not implemented](https://github.com/caraus-ecms/graphql/labels/not%20implemented)".
+For a more precise list of currently missing features see
+[issues](https://www.caraus.tech/projects/pub-graphql/issues).
 
 ## Documentation
 
 API documentation is available through
 [Hackage](https://hackage.haskell.org/package/graphql).
 
-You'll also find a small tutorial with some examples under
-[docs/tutorial](https://github.com/caraus-ecms/graphql/tree/master/docs/tutorial).
-
-## Further information
-
-- [Contributing guidelines](CONTRIBUTING.md).
-- [Changelog](CHANGELOG.md) – this one contains the most recent changes; 
-  individual changelogs for specific versions can be found on
-  [Hackage](https://hackage.haskell.org/package/graphql).
-
-## Contact
-
-Suggestions, contributions and bug reports are welcome.
-
-Should you have questions on usage, please open an issue and ask – this helps
-to write useful documentation.
-
-Feel free to contact on Slack in [#haskell on
-GraphQL](https://graphql.slack.com/messages/haskell/). You can obtain an
-invitation [here](https://graphql-slack.herokuapp.com/).
+Further documentation will be made available in the
+[Wiki](https://www.caraus.tech/projects/pub-graphql/wiki).

docs/tutorial/tutorial.lhs

@@ -1,151 +0,0 @@
----
-title: GraphQL Haskell Tutorial
----
-
-
-== Getting started ==
-
-Welcome to graphql-haskell!
-
-We have written a small tutorial to help you (and ourselves) understand the graphql package.
-
-Since this file is a literate haskell file, we start by importing some dependencies.
-
-> {-# LANGUAGE OverloadedStrings #-}
-> module Main where
->
-> import Control.Monad.IO.Class (liftIO)
-> import Data.Aeson (encode)
-> import Data.ByteString.Lazy.Char8 (putStrLn)
-> import Data.HashMap.Strict (HashMap)
-> import qualified Data.HashMap.Strict as HashMap
-> import Data.List.NonEmpty (NonEmpty(..))
-> import Data.Text (Text)
-> import Data.Time (getCurrentTime)
->
-> import Language.GraphQL
-> import qualified Language.GraphQL.Schema as Schema
->
-> import Prelude hiding (putStrLn)
-
-=== First example ===
-
-Now, as our first example, we are going to look at the
-example from [graphql.js](https://github.com/graphql/graphql-js).
-
-First we build a GraphQL schema.
-
-> schema1 :: HashMap Text (NonEmpty (Schema.Resolver IO))
-> schema1 = HashMap.singleton "Query" $ hello :| []
->
-> hello :: Schema.Resolver IO
-> hello = Schema.scalar "hello" (return ("it's me" :: Text))
-
-This defines a simple schema with one type and one field, that resolves to a fixed value.
-
-Next we define our query.
-
-> query1 :: Text
-> query1 = "{ hello }"
-
-
-To run the query, we call the `graphql` with the schema and the query.
-
-> main1 :: IO ()
-> main1 = putStrLn =<< encode <$> graphql schema1 query1
-
-This runs the query by fetching the one field defined,
-returning
-
-```{"data" : {"hello":"it's me"}}```
-
-
-
-=== Monadic actions ===
-
-For this example, we're going to be using time.
-
-> schema2 :: HashMap Text (NonEmpty (Schema.Resolver IO))
-> schema2 = HashMap.singleton "Query" $ time :| []
->
-> time :: Schema.Resolver IO
-> time = Schema.scalar "time" $ do
->   t <- liftIO getCurrentTime
->   return $ show t
-
-This defines a simple schema with one type and one field,
-which resolves to the current time.
-
-Next we define our query.
-
-> query2 :: Text
-> query2 = "{ time }"
->
-> main2 :: IO ()
-> main2 = putStrLn =<< encode <$> graphql schema2 query2
-
-This runs the query, returning the current time
-
-```{"data": {"time":"2016-03-08 23:28:14.546899 UTC"}}```
-
-
-=== Errors ===
-
-Errors are handled according to the spec,
-with fields that cause erros being resolved to `null`,
-and an error being added to the error list.
-
-An example of this is the following query:
-
-> queryShouldFail :: Text
-> queryShouldFail = "{ boyhowdy }"
-
-Since there is no `boyhowdy` field in our schema, it will not resolve,
-and the query will fail, as we can see in the following example.
-
-> mainShouldFail :: IO ()
-> mainShouldFail = do
->   success <- graphql schema1 query1
->   putStrLn $ encode success
->   putStrLn "This will fail"
->   failure <- graphql schema1 queryShouldFail
->   putStrLn $ encode failure
->
-
-This outputs:
-
-```
-{"data": {"hello": "it's me"}}
-This will fail
-{"data": {"boyhowdy": null}, "errors":[{"message": "the field boyhowdy did not resolve."}]}
-```
-
-=== Combining resolvers ===
-
-Now that we have two resolvers, we can define a schema which uses them both.
-
-> schema3 :: HashMap Text (NonEmpty (Schema.Resolver IO))
-> schema3 = HashMap.singleton "Query" $ hello :| [time]
->
-> query3 :: Text
-> query3 = "query timeAndHello { time hello }"
->
-> main3 :: IO ()
-> main3 = putStrLn =<< encode <$> graphql schema3 query3
-
-This queries for both time and hello, returning
-
-```{ "data": {"hello":"it's me","time":"2016-03-08 23:29:11.62108 UTC"}}```
-
-Notice that we can name our queries, as we did with `timeAndHello`. Since we have only been using single queries, we can use the shorthand `{ time hello}`, as we have been doing in the previous examples.
-
-In GraphQL there can only be one operation per query.
-
-
-== Further examples ==
-
-More examples on queries and a more complex schema can be found in the test directory,
-in the [Test.StarWars](../../tests/Test/StarWars) module. This includes a more complex schema, and more complex queries.
-
-> main :: IO ()
-> main = main1 >> main2 >> mainShouldFail >> main3

graphql.cabal

@@ -0,0 +1,116 @@
+cabal-version: 2.2
+
+-- This file has been generated from package.yaml by hpack version 0.33.0.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: c89b0164372b6e02e4f338d3865dd6bb9dfd1a4475f25d808450480d73f94f91
+
+name:           graphql
+version:        0.11.0.0
+synopsis:       Haskell GraphQL implementation
+description:    Haskell <https://spec.graphql.org/June2018/ GraphQL> implementation.
+category:       Language
+homepage:       https://www.caraus.tech/projects/pub-graphql
+bug-reports:    https://www.caraus.tech/projects/pub-graphql/issues
+author:         Danny Navarro <j@dannynavarro.net>,
+                Matthías Páll Gissurarson <mpg@mpg.is>,
+                Sólrún Halla Einarsdóttir <she@mpg.is>
+maintainer:     belka@caraus.de
+copyright:      (c) 2019-2020 Eugen Wissner,
+                (c) 2015-2017 J. Daniel Navarro
+license:        MPL-2.0 AND BSD-3-Clause
+license-files:  LICENSE,
+                LICENSE.MPL
+build-type:     Simple
+extra-source-files:
+    CHANGELOG.md
+    README.md
+
+source-repository head
+  type: git
+  location: git://caraus.tech/pub/graphql.git
+
+library
+  exposed-modules:
+      Language.GraphQL
+      Language.GraphQL.AST
+      Language.GraphQL.AST.DirectiveLocation
+      Language.GraphQL.AST.Document
+      Language.GraphQL.AST.Encoder
+      Language.GraphQL.AST.Lexer
+      Language.GraphQL.AST.Parser
+      Language.GraphQL.Error
+      Language.GraphQL.Execute
+      Language.GraphQL.Execute.Coerce
+      Language.GraphQL.Type
+      Language.GraphQL.Type.In
+      Language.GraphQL.Type.Out
+      Language.GraphQL.Type.Schema
+      Language.GraphQL.Validate
+      Language.GraphQL.Validate.Validation
+      Test.Hspec.GraphQL
+  other-modules:
+      Language.GraphQL.Execute.Execution
+      Language.GraphQL.Execute.Subscribe
+      Language.GraphQL.Execute.Transform
+      Language.GraphQL.Type.Definition
+      Language.GraphQL.Type.Internal
+      Language.GraphQL.Validate.Rules
+  hs-source-dirs:
+      src
+  build-depends:
+      aeson
+    , base >=4.7 && <5
+    , conduit
+    , containers
+    , exceptions
+    , hspec-expectations
+    , megaparsec
+    , parser-combinators
+    , scientific
+    , text
+    , transformers
+    , unordered-containers
+  default-language: Haskell2010
+
+test-suite graphql-test
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  other-modules:
+      Language.GraphQL.AST.EncoderSpec
+      Language.GraphQL.AST.LexerSpec
+      Language.GraphQL.AST.ParserSpec
+      Language.GraphQL.ErrorSpec
+      Language.GraphQL.Execute.CoerceSpec
+      Language.GraphQL.ExecuteSpec
+      Language.GraphQL.Type.OutSpec
+      Language.GraphQL.ValidateSpec
+      Test.DirectiveSpec
+      Test.FragmentSpec
+      Test.RootOperationSpec
+      Paths_graphql
+  autogen-modules:
+      Paths_graphql
+  hs-source-dirs:
+      tests
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      QuickCheck
+    , aeson
+    , base >=4.7 && <5
+    , conduit
+    , containers
+    , exceptions
+    , graphql
+    , hspec
+    , hspec-expectations
+    , hspec-megaparsec
+    , megaparsec
+    , parser-combinators
+    , raw-strings-qq
+    , scientific
+    , text
+    , transformers
+    , unordered-containers
+  default-language: Haskell2010

package.yaml

@@ -1,12 +1,15 @@
-name:                graphql
-version:             0.7.0.0
-synopsis:            Haskell GraphQL implementation
+name: graphql
+version: 0.11.0.0
+synopsis: Haskell GraphQL implementation
 description:
-  This package provides a rudimentary parser for the
-  <https://graphql.github.io/graphql-spec/June2018/ GraphQL> language.
-maintainer:          belka@caraus.de
-github:              caraus-ecms/graphql
-category:            Language
+  Haskell <https://spec.graphql.org/June2018/ GraphQL> implementation.
+maintainer: belka@caraus.de
+git: git://caraus.tech/pub/graphql.git
+homepage: https://www.caraus.tech/projects/pub-graphql
+bug-reports: https://www.caraus.tech/projects/pub-graphql/issues
+category: Language
+license: MPL-2.0 AND BSD-3-Clause
+
 copyright:
 - (c) 2019-2020 Eugen Wissner
 - (c) 2015-2017 J. Daniel Navarro
@@ -15,22 +18,23 @@ author:
 - Matthías Páll Gissurarson <mpg@mpg.is>
 - Sólrún Halla Einarsdóttir <she@mpg.is>
 
+license-file:
+- LICENSE
+- LICENSE.MPL
 extra-source-files:
 - CHANGELOG.md
 - README.md
-- LICENSE
-- docs/tutorial/tutorial.lhs
-
-data-files:
-- tests/data/*.graphql
-- tests/data/*.min.graphql
 
 dependencies:
 - aeson
 - base >= 4.7 && < 5
+- conduit
 - containers
+- exceptions
+- hspec-expectations
 - megaparsec
 - parser-combinators
+- scientific
 - text
 - transformers
 - unordered-containers
@@ -38,11 +42,15 @@ dependencies:
 library:
   source-dirs: src
   other-modules:
+  - Language.GraphQL.Execute.Execution
+  - Language.GraphQL.Execute.Subscribe
   - Language.GraphQL.Execute.Transform
-  - Language.GraphQL.Type.Directive
+  - Language.GraphQL.Type.Definition
+  - Language.GraphQL.Type.Internal
+  - Language.GraphQL.Validate.Rules
 
 tests:
-  tasty:
+  graphql-test:
     main: Spec.hs
     source-dirs: tests
     ghc-options:
@@ -52,7 +60,8 @@ tests:
     dependencies:
     - graphql
     - hspec
-    - hspec-expectations
     - hspec-megaparsec
     - QuickCheck
     - raw-strings-qq
+    generated-other-modules:
+    - Paths_graphql

semaphoreci.sh

@@ -1,40 +0,0 @@
-#!/bin/bash
-
-STACK=$SEMAPHORE_CACHE_DIR/stack
-export STACK_ROOT=$SEMAPHORE_CACHE_DIR/.stack
-
-setup() {
-	if [ ! -e "$STACK" ]
-	then
-		curl -L https://get.haskellstack.org/stable/linux-x86_64.tar.gz | tar xz --wildcards --strip-components=1 -C $SEMAPHORE_CACHE_DIR '*/stack'
-	fi
-	if [ -e "$SEMAPHORE_CACHE_DIR/graphql.cabal" ]
-	then
-		cp -a $SEMAPHORE_CACHE_DIR/graphql.cabal graphql.cabal
-	fi
-	$STACK --no-terminal setup
-	cp -a graphql.cabal $SEMAPHORE_CACHE_DIR/graphql.cabal
-}
-
-setup_test() {
-	$STACK --no-terminal test --only-snapshot
-}
-
-test() {
-	$STACK --no-terminal test --pedantic
-}
-
-test_docs() {
-	$STACK --no-terminal ghc -- -Wall -Werror -fno-code docs/tutorial/tutorial.lhs
-	$STACK --no-terminal haddock --no-haddock-deps
-}
-
-setup_lint() {
-	$STACK --no-terminal install hlint
-}
-
-lint() {
-	$STACK --no-terminal exec hlint -- src tests
-}
-
-$1

src/Language/GraphQL.hs

@@ -1,35 +1,75 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+
 -- | This module provides the functions to parse and execute @GraphQL@ queries.
 module Language.GraphQL
     ( graphql
     , graphqlSubs
     ) where
 
+import Control.Monad.Catch (MonadCatch)
 import qualified Data.Aeson as Aeson
-import Data.List.NonEmpty (NonEmpty)
-import Data.HashMap.Strict (HashMap)
+import qualified Data.Aeson.Types as Aeson
+import qualified Data.HashMap.Strict as HashMap
+import Data.Maybe (catMaybes)
+import qualified Data.Sequence as Seq
 import Data.Text (Text)
+import Language.GraphQL.AST
 import Language.GraphQL.Error
 import Language.GraphQL.Execute
-import Language.GraphQL.AST.Parser
-import qualified Language.GraphQL.Schema as Schema
+import qualified Language.GraphQL.Validate as Validate
+import Language.GraphQL.Type.Schema (Schema)
 import Text.Megaparsec (parse)
 
 -- | If the text parses correctly as a @GraphQL@ query the query is
--- executed using the given 'Schema.Resolver's.
-graphql :: Monad m
-    => HashMap Text (NonEmpty (Schema.Resolver m)) -- ^ Resolvers.
+-- executed using the given 'Schema'.
+graphql :: MonadCatch m
+    => Schema m -- ^ Resolvers.
     -> Text -- ^ Text representing a @GraphQL@ request document.
-    -> m Aeson.Value -- ^ Response.
-graphql = flip graphqlSubs mempty
+    -> m (Either (ResponseEventStream m Aeson.Value) Aeson.Object) -- ^ Response.
+graphql schema = graphqlSubs schema mempty mempty
 
 -- | If the text parses correctly as a @GraphQL@ query the substitution is
 -- applied to the query and the query is then executed using to the given
--- 'Schema.Resolver's.
-graphqlSubs :: Monad m
-    => HashMap Text (NonEmpty (Schema.Resolver m)) -- ^ Resolvers.
-    -> Schema.Subs -- ^ Variable substitution function.
+-- 'Schema'.
+graphqlSubs :: MonadCatch m
+    => Schema m -- ^ Resolvers.
+    -> Maybe Text -- ^ Operation name.
+    -> Aeson.Object -- ^ Variable substitution function.
     -> Text -- ^ Text representing a @GraphQL@ request document.
-    -> m Aeson.Value -- ^ Response.
-graphqlSubs schema f
-    = either parseError (execute schema f)
-    . parse document ""
+    -> m (Either (ResponseEventStream m Aeson.Value) Aeson.Object) -- ^ Response.
+graphqlSubs schema operationName variableValues document' =
+    case parse document "" document' of
+        Left errorBundle -> pure . formatResponse <$> parseError errorBundle
+        Right parsed ->
+            case validate parsed of
+                Seq.Empty -> fmap formatResponse
+                    <$> execute schema operationName variableValues parsed
+                errors -> pure $ pure
+                    $ HashMap.singleton "errors"
+                    $ Aeson.toJSON
+                    $ fromValidationError <$> errors
+  where
+    validate = Validate.document schema Validate.specifiedRules
+    formatResponse (Response data'' Seq.Empty) = HashMap.singleton "data" data''
+    formatResponse (Response data'' errors') = HashMap.fromList
+        [ ("data", data'')
+        , ("errors", Aeson.toJSON $ fromError <$> errors')
+        ]
+    fromError Error{..} = Aeson.object $ catMaybes
+        [ Just ("message", Aeson.toJSON message)
+        , toMaybe fromLocation "locations" locations
+        , toMaybe fromPath "path" path
+        ]
+    fromValidationError Validate.Error{..} = Aeson.object
+        [ ("message", Aeson.toJSON message)
+        , ("locations", Aeson.listValue fromLocation locations)
+        ]
+    toMaybe _ _ [] = Nothing
+    toMaybe f key xs = Just (key, Aeson.listValue f xs)
+    fromPath (Segment segment) = Aeson.String segment
+    fromPath (Index index) = Aeson.toJSON index
+    fromLocation Location{..} = Aeson.object
+        [ ("line", Aeson.toJSON line)
+        , ("column", Aeson.toJSON column)
+        ]

src/Language/GraphQL/AST.hs

@@ -1,6 +1,12 @@
--- | Target AST for Parser.
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+-- | Target AST for parser.
 module Language.GraphQL.AST
     ( module Language.GraphQL.AST.Document
+    , module Language.GraphQL.AST.Parser
     ) where
 
 import Language.GraphQL.AST.Document
+import Language.GraphQL.AST.Parser

src/Language/GraphQL/AST/Core.hs

@@ -1,78 +0,0 @@
--- | This is the AST meant to be executed.
-module Language.GraphQL.AST.Core
-    ( Alias
-    , Arguments(..)
-    , Directive(..)
-    , Document
-    , Field(..)
-    , Fragment(..)
-    , Name
-    , Operation(..)
-    , Selection(..)
-    , TypeCondition
-    , Value(..)
-    ) where
-
-import Data.Int (Int32)
-import Data.HashMap.Strict (HashMap)
-import Data.List.NonEmpty (NonEmpty)
-import Data.Sequence (Seq)
-import Data.String (IsString(..))
-import Data.Text (Text)
-import Language.GraphQL.AST (Alias, Name, TypeCondition)
-
--- | GraphQL document is a non-empty list of operations.
-type Document = NonEmpty Operation
-
--- | GraphQL has 3 operation types: queries, mutations and subscribtions.
---
--- Currently only queries and mutations are supported.
-data Operation
-    = Query (Maybe Text) (Seq Selection)
-    | Mutation (Maybe Text) (Seq Selection)
-    deriving (Eq, Show)
-
--- | Single GraphQL field.
-data Field
-    = Field (Maybe Alias) Name Arguments (Seq Selection)
-    deriving (Eq, Show)
-
--- | Argument list.
-newtype Arguments = Arguments (HashMap Name Value)
-    deriving (Eq, Show)
-
-instance Semigroup Arguments where
-    (Arguments x) <> (Arguments y) = Arguments $ x <> y
-
-instance Monoid Arguments where
-    mempty = Arguments mempty
-
--- | Directive.
-data Directive = Directive Name Arguments
-    deriving (Eq, Show)
-
--- | Represents fragments and inline fragments.
-data Fragment
-    = Fragment TypeCondition (Seq Selection)
-    deriving (Eq, Show)
-
--- | Single selection element.
-data Selection
-    = SelectionFragment Fragment
-    | SelectionField Field
-    deriving (Eq, Show)
-
--- | Represents accordingly typed GraphQL values.
-data Value
-    = Int Int32
-    | Float Double -- ^ GraphQL Float is double precision
-    | String Text
-    | Boolean Bool
-    | Null
-    | Enum Name
-    | List [Value]
-    | Object (HashMap Name Value)
-    deriving (Eq, Show)
-
-instance IsString Value where
-    fromString = String . fromString

src/Language/GraphQL/AST/DirectiveLocation.hs

@@ -1,5 +1,11 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE Safe #-}
+
 -- | Various parts of a GraphQL document can be annotated with directives. 
---   This module describes locations in a document where directives can appear.
+-- This module describes locations in a document where directives can appear.
 module Language.GraphQL.AST.DirectiveLocation
     ( DirectiveLocation(..)
     , ExecutableDirectiveLocation(..)
@@ -7,12 +13,18 @@ module Language.GraphQL.AST.DirectiveLocation
     ) where
 
 -- | All directives can be splitted in two groups: directives used to annotate
---   various parts of executable definitions and the ones used in the schema
---   definition.
+-- various parts of executable definitions and the ones used in the schema
+-- definition.
 data DirectiveLocation
     = ExecutableDirectiveLocation ExecutableDirectiveLocation
     | TypeSystemDirectiveLocation TypeSystemDirectiveLocation
-    deriving (Eq, Show)
+    deriving Eq
+
+instance Show DirectiveLocation where
+    show (ExecutableDirectiveLocation directiveLocation) =
+        show directiveLocation
+    show (TypeSystemDirectiveLocation directiveLocation) =
+        show directiveLocation
 
 -- | Where directives can appear in an executable definition, like a query.
 data ExecutableDirectiveLocation
@@ -23,7 +35,16 @@ data ExecutableDirectiveLocation
     | FragmentDefinition
     | FragmentSpread
     | InlineFragment
-    deriving (Eq, Show)
+    deriving Eq
+
+instance Show ExecutableDirectiveLocation where
+    show Query = "QUERY"
+    show Mutation = "MUTATION"
+    show Subscription = "SUBSCRIPTION"
+    show Field = "FIELD"
+    show FragmentDefinition = "FRAGMENT_DEFINITION"
+    show FragmentSpread = "FRAGMENT_SPREAD"
+    show InlineFragment = "INLINE_FRAGMENT"
 
 -- | Where directives can appear in a type system definition.
 data TypeSystemDirectiveLocation
@@ -38,4 +59,17 @@ data TypeSystemDirectiveLocation
     | EnumValue
     | InputObject
     | InputFieldDefinition
-    deriving (Eq, Show)
+    deriving Eq
+
+instance Show TypeSystemDirectiveLocation where
+    show Schema = "SCHEMA"
+    show Scalar = "SCALAR"
+    show Object = "OBJECT"
+    show FieldDefinition = "FIELD_DEFINITION"
+    show ArgumentDefinition = "ARGUMENT_DEFINITION"
+    show Interface = "INTERFACE"
+    show Union = "UNION"
+    show Enum = "ENUM"
+    show EnumValue = "ENUM_VALUE"
+    show InputObject = "INPUT_OBJECT"
+    show InputFieldDefinition = "INPUT_FIELD_DEFINITION"

src/Language/GraphQL/AST/Document.hs

@@ -1,25 +1,34 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE Safe #-}
 
 -- | This module defines an abstract syntax tree for the @GraphQL@ language. It
 -- follows closely the structure given in the specification. Please refer to
 -- <https://facebook.github.io/graphql/ Facebook's GraphQL Specification>.
 -- for more information.
 module Language.GraphQL.AST.Document
-    ( Alias
-    , Argument(..)
+    ( Argument(..)
     , ArgumentsDefinition(..)
+    , ConstValue(..)
     , Definition(..)
     , Description(..)
     , Directive(..)
     , Document
     , EnumValueDefinition(..)
     , ExecutableDefinition(..)
+    , Field(..)
     , FieldDefinition(..)
     , FragmentDefinition(..)
+    , FragmentSpread(..)
     , ImplementsInterfaces(..)
+    , InlineFragment(..)
     , InputValueDefinition(..)
+    , Location(..)
     , Name
     , NamedType
+    , Node(..)
     , NonNullType(..)
     , ObjectField(..)
     , OperationDefinition(..)
@@ -45,7 +54,7 @@ import Data.Int (Int32)
 import Data.List.NonEmpty (NonEmpty)
 import Data.Text (Text)
 import qualified Data.Text as Text
-import Language.GraphQL.AST.DirectiveLocation
+import Language.GraphQL.AST.DirectiveLocation (DirectiveLocation)
 
 -- * Language
 
@@ -54,6 +63,27 @@ import Language.GraphQL.AST.DirectiveLocation
 -- | Name.
 type Name = Text
 
+-- | Error location, line and column.
+data Location = Location
+    { line :: Word
+    , column :: Word
+    } deriving (Eq, Show)
+
+instance Ord Location where
+    compare (Location thisLine thisColumn) (Location thatLine thatColumn)
+        | thisLine < thatLine = LT
+        | thisLine > thatLine = GT
+        | otherwise = compare thisColumn thatColumn
+
+-- | Contains some tree node with a location.
+data Node a = Node
+    { node :: a
+    , location :: Location
+    } deriving (Eq, Show)
+
+instance Functor Node where
+    fmap f Node{..} = Node (f node) location
+
 -- ** Document
 
 -- | GraphQL document.
@@ -62,8 +92,8 @@ type Document = NonEmpty Definition
 -- | All kinds of definitions that can occur in a GraphQL document.
 data Definition
     = ExecutableDefinition ExecutableDefinition
-    | TypeSystemDefinition TypeSystemDefinition
-    | TypeSystemExtension TypeSystemExtension
+    | TypeSystemDefinition TypeSystemDefinition Location
+    | TypeSystemExtension TypeSystemExtension Location
     deriving (Eq, Show)
 
 -- | Top-level definition of a document, either an operation or a fragment.
@@ -76,13 +106,14 @@ data ExecutableDefinition
 
 -- | Operation definition.
 data OperationDefinition
-    = SelectionSet SelectionSet
+    = SelectionSet SelectionSet Location
     | OperationDefinition
         OperationType
         (Maybe Name)
         [VariableDefinition]
         [Directive]
         SelectionSet
+        Location
     deriving (Eq, Show)
 
 -- | GraphQL has 3 operation types:
@@ -91,9 +122,7 @@ data OperationDefinition
 -- * mutation - a write operation followed by a fetch.
 -- * subscription - a long-lived request that fetches data in response to
 -- source events.
---
--- Currently only queries and mutations are supported.
-data OperationType = Query | Mutation deriving (Eq, Show)
+data OperationType = Query | Mutation | Subscription deriving (Eq, Show)
 
 -- ** Selection Sets
 
@@ -103,10 +132,15 @@ type SelectionSet = NonEmpty Selection
 -- | Field selection.
 type SelectionSetOpt = [Selection]
 
--- | Selection is a single entry in a selection set. It can be a single field,
--- fragment spread or inline fragment.
---
--- The only required property of a field is its name. Optionally it can also
+-- | Selection is a single entry in a selection set. It can be a single 'Field',
+-- 'FragmentSpread' or an 'InlineFragment'.
+data Selection
+    = FieldSelection Field
+    | FragmentSpreadSelection FragmentSpread
+    | InlineFragmentSelection InlineFragment
+    deriving (Eq, Show)
+
+-- | The only required property of a field is its name. Optionally it can also
 -- have an alias, arguments, directives and a list of subfields.
 --
 -- In the following query "user" is a field with two subfields, "id" and "name":
@@ -119,8 +153,27 @@ type SelectionSetOpt = [Selection]
 --   }
 -- }
 -- @
+data Field =
+    Field (Maybe Name) Name [Argument] [Directive] SelectionSetOpt Location
+    deriving (Eq, Show)
+
+-- | Inline fragments don't have any name and the type condition ("on UserType")
+-- is optional.
 --
--- A fragment spread refers to a fragment defined outside the operation and is
+-- @
+-- {
+--   user {
+--     ... on UserType {
+--       id
+--       name
+--     }
+-- }
+-- @
+data InlineFragment = InlineFragment
+    (Maybe TypeCondition) [Directive] SelectionSet Location
+    deriving (Eq, Show)
+
+-- | A fragment spread refers to a fragment defined outside the operation and is
 -- expanded at the execution time.
 --
 -- @
@@ -135,23 +188,7 @@ type SelectionSetOpt = [Selection]
 --   name
 -- }
 -- @
---
--- Inline fragments are similar but they don't have any name and the type
--- condition ("on UserType") is optional.
---
--- @
--- {
---   user {
---     ... on UserType {
---       id
---       name
---     }
--- }
--- @
-data Selection
-    = Field (Maybe Alias) Name [Argument] [Directive] SelectionSetOpt
-    | FragmentSpread Name [Directive]
-    | InlineFragment (Maybe TypeCondition) [Directive] SelectionSet
+data FragmentSpread = FragmentSpread Name [Directive] Location
     deriving (Eq, Show)
 
 -- ** Arguments
@@ -167,29 +204,13 @@ data Selection
 -- @
 --
 --  Here "id" is an argument for the field "user" and its value is 4.
-data Argument = Argument Name Value deriving (Eq,Show)
-
--- ** Field Alias
-
--- | Alternative field name.
---
--- @
--- {
---   smallPic: profilePic(size: 64)
---   bigPic: profilePic(size: 1024)
--- }
--- @
---
--- Here "smallPic" and "bigPic" are aliases for the same field, "profilePic",
--- used to distinquish between profile pictures with different arguments
--- (sizes).
-type Alias = Name
+data Argument = Argument Name (Node Value) Location deriving (Eq, Show)
 
 -- ** Fragments
 
 -- | Fragment definition.
 data FragmentDefinition
-    = FragmentDefinition Name TypeCondition [Directive] SelectionSet
+    = FragmentDefinition Name TypeCondition [Directive] SelectionSet Location
     deriving (Eq, Show)
 
 -- | Type condition.
@@ -197,7 +218,7 @@ type TypeCondition = Name
 
 -- ** Input Values
 
--- | Input value.
+-- | Input value (literal or variable).
 data Value
     = Variable Name
     | Int Int32
@@ -207,18 +228,50 @@ data Value
     | Null
     | Enum Name
     | List [Value]
-    | Object [ObjectField]
+    | Object [ObjectField Value]
+    deriving (Eq, Show)
+
+-- | Constant input value.
+data ConstValue
+    = ConstInt Int32
+    | ConstFloat Double
+    | ConstString Text
+    | ConstBoolean Bool
+    | ConstNull
+    | ConstEnum Name
+    | ConstList [ConstValue]
+    | ConstObject [ObjectField ConstValue]
     deriving (Eq, Show)
 
 -- | Key-value pair.
 --
---   A list of 'ObjectField's represents a GraphQL object type.
-data ObjectField = ObjectField Name Value deriving (Eq, Show)
+-- A list of 'ObjectField's represents a GraphQL object type.
+data ObjectField a = ObjectField
+    { name :: Name
+    , value :: Node a
+    , location :: Location
+    } deriving (Eq, Show)
 
 -- ** Variables
 
 -- | Variable definition.
-data VariableDefinition = VariableDefinition Name Type (Maybe Value)
+--
+-- Each operation can include a list of variables:
+--
+-- @
+-- query (protagonist: String = "Zarathustra") {
+--   getAuthor(protagonist: $protagonist)
+-- }
+-- @
+--
+-- This query defines an optional variable @protagonist@ of type @String@,
+-- its default value is "Zarathustra". If no default value is defined and no
+-- value is provided, a variable can still be @null@ if its type is nullable.
+--
+-- Variables are usually passed along with the query, but not in the query
+-- itself. They make queries reusable.
+data VariableDefinition =
+    VariableDefinition Name Type (Maybe (Node ConstValue)) Location
     deriving (Eq, Show)
 
 -- ** Type References
@@ -245,7 +298,7 @@ data NonNullType
 --
 -- Directives begin with "@", can accept arguments, and can be applied to the
 -- most GraphQL elements, providing additional information.
-data Directive = Directive Name [Argument] deriving (Eq, Show)
+data Directive = Directive Name [Argument] Location deriving (Eq, Show)
 
 -- * Type System
 
@@ -444,8 +497,8 @@ instance Monoid ArgumentsDefinition where
 -- @
 --
 -- The input type "Point2D" contains two value definitions: "x" and "y".
-data InputValueDefinition
-    = InputValueDefinition Description Name Type (Maybe Value) [Directive]
+data InputValueDefinition = InputValueDefinition
+    Description Name Type (Maybe (Node ConstValue)) [Directive]
     deriving (Eq, Show)
 
 -- ** Unions

src/Language/GraphQL/AST/Encoder.hs

@@ -1,5 +1,8 @@
-{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE Safe #-}
 
 -- | This module defines a minifier and a printer for the @GraphQL@ language.
 module Language.GraphQL.AST.Encoder
@@ -24,8 +27,7 @@ import Data.Text.Lazy.Builder (Builder)
 import qualified Data.Text.Lazy.Builder as Builder
 import Data.Text.Lazy.Builder.Int (decimal, hexadecimal)
 import Data.Text.Lazy.Builder.RealFloat (realFloat)
-import qualified Language.GraphQL.AST as Full
-import Language.GraphQL.AST.Document
+import qualified Language.GraphQL.AST.Document as Full
 
 -- | Instructs the encoder whether the GraphQL document should be minified or
 --   pretty printed.
@@ -44,17 +46,18 @@ minified :: Formatter
 minified = Minified
 
 -- | Converts a Document' into a string.
-document :: Formatter -> Document -> Lazy.Text
+document :: Formatter -> Full.Document -> Lazy.Text
 document formatter defs
     | Pretty _ <- formatter = Lazy.Text.intercalate "\n" encodeDocument
     | Minified <-formatter = Lazy.Text.snoc (mconcat encodeDocument) '\n'
   where
     encodeDocument = foldr executableDefinition [] defs
-    executableDefinition (ExecutableDefinition x) acc = definition formatter x : acc
+    executableDefinition (Full.ExecutableDefinition executableDefinition') acc =
+        definition formatter executableDefinition' : acc
     executableDefinition _ acc = acc
 
 -- | Converts a t'Full.ExecutableDefinition' into a string.
-definition :: Formatter -> ExecutableDefinition -> Lazy.Text
+definition :: Formatter -> Full.ExecutableDefinition -> Lazy.Text
 definition formatter x
     | Pretty _ <- formatter = Lazy.Text.snoc (encodeDefinition x) '\n'
     | Minified <- formatter = encodeDefinition x
@@ -66,42 +69,45 @@ definition formatter x
 
 -- | Converts a 'Full.OperationDefinition into a string.
 operationDefinition :: Formatter -> Full.OperationDefinition -> Lazy.Text
-operationDefinition formatter (Full.SelectionSet sels)
-    = selectionSet formatter sels
-operationDefinition formatter (Full.OperationDefinition Full.Query name vars dirs sels)
-    = "query " <> node formatter name vars dirs sels
-operationDefinition formatter (Full.OperationDefinition Full.Mutation name vars dirs sels)
-    = "mutation " <> node formatter name vars dirs sels
-
--- | Converts a Full.Query or Full.Mutation into a string.
-node :: Formatter ->
-    Maybe Full.Name ->
-    [Full.VariableDefinition] ->
-    [Full.Directive] ->
-    Full.SelectionSet ->
-    Lazy.Text
-node formatter name vars dirs sels
-    = Lazy.Text.fromStrict (fold name)
-    <> optempty (variableDefinitions formatter) vars
-    <> optempty (directives formatter) dirs
-    <> eitherFormat formatter " " mempty
-    <> selectionSet formatter sels
+operationDefinition formatter = \case
+    Full.SelectionSet sels _ -> selectionSet formatter sels
+    Full.OperationDefinition Full.Query name vars dirs sels _ ->
+        "query " <> root name vars dirs sels
+    Full.OperationDefinition Full.Mutation name vars dirs sels _ ->
+        "mutation " <> root name vars dirs sels
+    Full.OperationDefinition Full.Subscription name vars dirs sels _ ->
+        "subscription " <> root name vars dirs sels
+  where
+    -- | Converts a Query or Mutation into a string.
+    root :: Maybe Full.Name ->
+        [Full.VariableDefinition] ->
+        [Full.Directive] ->
+        Full.SelectionSet ->
+        Lazy.Text
+    root name vars dirs sels
+        = Lazy.Text.fromStrict (fold name)
+        <> optempty (variableDefinitions formatter) vars
+        <> optempty (directives formatter) dirs
+        <> eitherFormat formatter " " mempty
+        <> selectionSet formatter sels
 
 variableDefinitions :: Formatter -> [Full.VariableDefinition] -> Lazy.Text
 variableDefinitions formatter
     = parensCommas formatter $ variableDefinition formatter
 
 variableDefinition :: Formatter -> Full.VariableDefinition -> Lazy.Text
-variableDefinition formatter (Full.VariableDefinition var ty dv)
-    = variable var
+variableDefinition formatter variableDefinition' =
+    let Full.VariableDefinition variableName variableType defaultValue' _ =
+            variableDefinition'
+     in variable variableName
     <> eitherFormat formatter ": " ":"
-    <> type' ty
-    <> maybe mempty (defaultValue formatter) dv
+    <> type' variableType
+    <> maybe mempty (defaultValue formatter) (Full.node <$> defaultValue')
 
-defaultValue :: Formatter -> Full.Value -> Lazy.Text
+defaultValue :: Formatter -> Full.ConstValue -> Lazy.Text
 defaultValue formatter val
     = eitherFormat formatter " = " "="
-    <> value formatter val
+    <> value formatter (fromConstValue val)
 
 variable :: Full.Name -> Lazy.Text
 variable var = "$" <> Lazy.Text.fromStrict var
@@ -123,12 +129,12 @@ indent indentation = Lazy.Text.replicate (fromIntegral indentation) indentSymbol
 selection :: Formatter -> Full.Selection -> Lazy.Text
 selection formatter = Lazy.Text.append indent' . encodeSelection
   where
-    encodeSelection (Full.Field alias name args directives' selections) =
-        field incrementIndent alias name args directives' selections
-    encodeSelection (Full.InlineFragment typeCondition directives' selections) =
-        inlineFragment incrementIndent typeCondition directives' selections
-    encodeSelection (Full.FragmentSpread name directives') =
-        fragmentSpread incrementIndent name directives'
+    encodeSelection (Full.FieldSelection fieldSelection) =
+        field incrementIndent fieldSelection
+    encodeSelection (Full.InlineFragmentSelection fragmentSelection) =
+        inlineFragment incrementIndent fragmentSelection
+    encodeSelection (Full.FragmentSpreadSelection fragmentSelection) =
+        fragmentSpread incrementIndent fragmentSelection
     incrementIndent
         | Pretty indentation <- formatter = Pretty $ indentation + 1
         | otherwise = Minified
@@ -139,15 +145,9 @@ selection formatter = Lazy.Text.append indent' . encodeSelection
 colon :: Formatter -> Lazy.Text
 colon formatter = eitherFormat formatter ": " ":"
 
--- | Converts Full.Field into a string
-field :: Formatter ->
-    Maybe Full.Name ->
-    Full.Name ->
-    [Full.Argument] ->
-    [Full.Directive] ->
-    [Full.Selection] ->
-    Lazy.Text
-field formatter alias name args dirs set
+-- | Converts Field into a string.
+field :: Formatter -> Full.Field -> Lazy.Text
+field formatter (Full.Field alias name args dirs set _)
     = optempty prependAlias (fold alias)
     <> Lazy.Text.fromStrict name
     <> optempty (arguments formatter) args
@@ -162,32 +162,28 @@ arguments :: Formatter -> [Full.Argument] -> Lazy.Text
 arguments formatter = parensCommas formatter $ argument formatter
 
 argument :: Formatter -> Full.Argument -> Lazy.Text
-argument formatter (Full.Argument name value')
+argument formatter (Full.Argument name value' _)
     = Lazy.Text.fromStrict name
     <> colon formatter
-    <> value formatter value'
+    <> value formatter (Full.node value')
 
 -- * Fragments
 
-fragmentSpread :: Formatter -> Full.Name -> [Full.Directive] -> Lazy.Text
-fragmentSpread formatter name directives'
+fragmentSpread :: Formatter -> Full.FragmentSpread -> Lazy.Text
+fragmentSpread formatter (Full.FragmentSpread name directives' _)
     = "..." <> Lazy.Text.fromStrict name
     <> optempty (directives formatter) directives'
 
-inlineFragment ::
-    Formatter ->
-    Maybe Full.TypeCondition ->
-    [Full.Directive] ->
-    Full.SelectionSet ->
-    Lazy.Text
-inlineFragment formatter tc dirs sels = "... on "
-    <> Lazy.Text.fromStrict (fold tc)
-    <> directives formatter dirs
+inlineFragment :: Formatter -> Full.InlineFragment -> Lazy.Text
+inlineFragment formatter (Full.InlineFragment typeCondition directives' selections _)
+    = "... on "
+    <> Lazy.Text.fromStrict (fold typeCondition)
+    <> directives formatter directives'
     <> eitherFormat formatter " " mempty
-    <> selectionSet formatter sels
+    <> selectionSet formatter selections
 
 fragmentDefinition :: Formatter -> Full.FragmentDefinition -> Lazy.Text
-fragmentDefinition formatter (Full.FragmentDefinition name tc dirs sels)
+fragmentDefinition formatter (Full.FragmentDefinition name tc dirs sels _)
     = "fragment " <> Lazy.Text.fromStrict name
     <> " on " <> Lazy.Text.fromStrict tc
     <> optempty (directives formatter) dirs
@@ -198,7 +194,7 @@ fragmentDefinition formatter (Full.FragmentDefinition name tc dirs sels)
 
 -- | Converts a 'Full.Directive' into a string.
 directive :: Formatter -> Full.Directive -> Lazy.Text
-directive formatter (Full.Directive name args)
+directive formatter (Full.Directive name args _)
     = "@" <> Lazy.Text.fromStrict name <> optempty (arguments formatter) args
 
 directives :: Formatter -> [Full.Directive] -> Lazy.Text
@@ -217,6 +213,19 @@ value _ (Full.Enum x) = Lazy.Text.fromStrict x
 value formatter (Full.List x) = listValue formatter x
 value formatter (Full.Object x) = objectValue formatter x
 
+fromConstValue :: Full.ConstValue -> Full.Value
+fromConstValue (Full.ConstInt x) = Full.Int x
+fromConstValue (Full.ConstFloat x) = Full.Float x
+fromConstValue (Full.ConstBoolean  x) = Full.Boolean x
+fromConstValue Full.ConstNull = Full.Null
+fromConstValue (Full.ConstString string) = Full.String string
+fromConstValue (Full.ConstEnum x) = Full.Enum x
+fromConstValue (Full.ConstList x) = Full.List $ fromConstValue <$> x
+fromConstValue (Full.ConstObject x) = Full.Object $ fromConstObjectField <$> x
+  where
+    fromConstObjectField Full.ObjectField{value = value', ..} =
+        Full.ObjectField name (fromConstValue <$> value') location
+
 booleanValue :: Bool -> Lazy.Text
 booleanValue True  = "true"
 booleanValue False = "false"
@@ -242,19 +251,20 @@ stringValue (Pretty indentation) string =
           char == '\t' || isNewline char || (char >= '\x0020' && char /= '\x007F')
 
       tripleQuote = Builder.fromText "\"\"\""
-      start = tripleQuote <> Builder.singleton '\n'
-      end = Builder.fromLazyText (indent indentation) <> tripleQuote
+      newline = Builder.singleton '\n'
 
       strip = Text.dropWhile isWhiteSpace . Text.dropWhileEnd isWhiteSpace
       lines' = map Builder.fromText $ Text.split isNewline (Text.replace "\r\n" "\n" $ strip string)
       encoded [] = oneLine string
       encoded [_] = oneLine string
-      encoded lines'' = start <> transformLines lines'' <> end
-      transformLines = foldr ((\line acc -> line <> Builder.singleton '\n' <> acc) . transformLine) mempty
-      transformLine line =
-        if Lazy.Text.null (Builder.toLazyText line)
-        then line
-        else Builder.fromLazyText (indent (indentation + 1)) <> line
+      encoded lines'' = tripleQuote <> newline
+        <> transformLines lines''
+        <> Builder.fromLazyText (indent indentation) <> tripleQuote
+      transformLines = foldr transformLine mempty
+      transformLine "" acc = newline <> acc
+      transformLine line' acc
+            = Builder.fromLazyText (indent (indentation + 1))
+            <> line' <> newline <> acc
 
 escape :: Char -> Builder
 escape char'
@@ -274,7 +284,7 @@ escape char'
 listValue :: Formatter -> [Full.Value] -> Lazy.Text
 listValue formatter = bracketsCommas formatter $ value formatter
 
-objectValue :: Formatter -> [Full.ObjectField] -> Lazy.Text
+objectValue :: Formatter -> [Full.ObjectField Full.Value] -> Lazy.Text
 objectValue formatter = intercalate $ objectField formatter
   where
     intercalate f
@@ -282,14 +292,14 @@ objectValue formatter = intercalate $ objectField formatter
         . Lazy.Text.intercalate (eitherFormat formatter ", " ",")
         . fmap f
 
-objectField :: Formatter -> Full.ObjectField -> Lazy.Text
-objectField formatter (Full.ObjectField name value') =
+objectField :: Formatter -> Full.ObjectField Full.Value -> Lazy.Text
+objectField formatter (Full.ObjectField name (Full.Node value' _) _) =
     Lazy.Text.fromStrict name <> colon formatter <> value formatter value'
 
 -- | Converts a 'Full.Type' a type into a string.
 type' :: Full.Type -> Lazy.Text
-type' (Full.TypeNamed   x) = Lazy.Text.fromStrict x
-type' (Full.TypeList    x) = listType x
+type' (Full.TypeNamed x) = Lazy.Text.fromStrict x
+type' (Full.TypeList x) = listType x
 type' (Full.TypeNonNull x) = nonNullType x
 
 listType :: Full.Type -> Lazy.Text
@@ -297,7 +307,7 @@ listType x = brackets (type' x)
 
 nonNullType :: Full.NonNullType -> Lazy.Text
 nonNullType (Full.NonNullTypeNamed x) = Lazy.Text.fromStrict x <> "!"
-nonNullType (Full.NonNullTypeList  x) = listType x <> "!"
+nonNullType (Full.NonNullTypeList x) = listType x <> "!"
 
 -- * Internal
 

src/Language/GraphQL/AST/Lexer.hs

@@ -92,16 +92,16 @@ dollar :: Parser T.Text
 dollar = symbol "$"
 
 -- | Parser for "@".
-at :: Parser Text
-at = symbol "@"
+at :: Parser ()
+at = symbol "@" >> pure ()
 
 -- | Parser for "&".
 amp :: Parser T.Text
 amp = symbol "&"
 
 -- | Parser for ":".
-colon :: Parser T.Text
-colon = symbol ":"
+colon :: Parser ()
+colon = symbol ":" >> pure ()
 
 -- | Parser for "=".
 equals :: Parser T.Text
@@ -168,11 +168,11 @@ blockString = between "\"\"\"" "\"\"\"" stringValue <* spaceConsumer
 
 -- | Parser for integers.
 integer :: Integral a => Parser a
-integer = Lexer.signed (pure ()) $ lexeme Lexer.decimal
+integer = Lexer.signed (pure ()) (lexeme Lexer.decimal) <?> "IntValue"
 
 -- | Parser for floating-point numbers.
 float :: Parser Double
-float = Lexer.signed (pure ()) $ lexeme Lexer.float
+float = Lexer.signed (pure ()) (lexeme Lexer.float) <?> "FloatValue"
 
 -- | Parser for names (/[_A-Za-z][_0-9A-Za-z]*/).
 name :: Parser T.Text
@@ -233,4 +233,4 @@ extend token extensionLabel parsers
     tryExtension extensionParser = try
         $ symbol "extend"
         *> symbol token
-        *> extensionParser
+        *> extensionParser

src/Language/GraphQL/AST/Parser.hs

@@ -1,12 +1,14 @@
+{-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
 
 -- | @GraphQL@ document parser.
 module Language.GraphQL.AST.Parser
     ( document
     ) where
 
-import Control.Applicative (Alternative(..), optional)
+import Control.Applicative (Alternative(..), liftA2, optional)
 import Control.Applicative.Combinators (sepBy1)
 import qualified Control.Applicative.Combinators.NonEmpty as NonEmpty
 import Data.List.NonEmpty (NonEmpty(..))
@@ -17,42 +19,70 @@ import Language.GraphQL.AST.DirectiveLocation
     , ExecutableDirectiveLocation
     , TypeSystemDirectiveLocation
     )
-import Language.GraphQL.AST.Document
+import qualified Language.GraphQL.AST.Document as Full
 import Language.GraphQL.AST.Lexer
-import Text.Megaparsec (lookAhead, option, try, (<?>))
+import Text.Megaparsec
+    ( MonadParsec(..)
+    , SourcePos(..)
+    , getSourcePos
+    , lookAhead
+    , option
+    , try
+    , unPos
+    , (<?>)
+    )
 
 -- | Parser for the GraphQL documents.
-document :: Parser Document
+document :: Parser Full.Document
 document = unicodeBOM
-    >> spaceConsumer
-    >> lexeme (NonEmpty.some definition)
+    *> spaceConsumer
+    *> lexeme (NonEmpty.some definition)
 
-definition :: Parser Definition
-definition = ExecutableDefinition <$> executableDefinition
-    <|> TypeSystemDefinition <$> typeSystemDefinition
-    <|> TypeSystemExtension <$> typeSystemExtension
+definition :: Parser Full.Definition
+definition = Full.ExecutableDefinition <$> executableDefinition
+    <|> typeSystemDefinition'
+    <|> typeSystemExtension'
     <?> "Definition"
+  where
+    typeSystemDefinition' = do
+        location <- getLocation
+        definition' <- typeSystemDefinition
+        pure $ Full.TypeSystemDefinition definition' location
+    typeSystemExtension' = do
+        location <- getLocation
+        definition' <- typeSystemExtension
+        pure $ Full.TypeSystemExtension definition' location
 
-executableDefinition :: Parser ExecutableDefinition
-executableDefinition = DefinitionOperation <$> operationDefinition
-    <|> DefinitionFragment  <$> fragmentDefinition
+getLocation :: Parser Full.Location
+getLocation = fromSourcePosition <$> getSourcePos
+  where
+    fromSourcePosition SourcePos{..} =
+        Full.Location (wordFromPosition sourceLine) (wordFromPosition sourceColumn)
+    wordFromPosition = fromIntegral . unPos
+
+executableDefinition :: Parser Full.ExecutableDefinition
+executableDefinition = Full.DefinitionOperation <$> operationDefinition
+    <|> Full.DefinitionFragment  <$> fragmentDefinition
     <?> "ExecutableDefinition"
 
-typeSystemDefinition :: Parser TypeSystemDefinition
+typeSystemDefinition :: Parser Full.TypeSystemDefinition
 typeSystemDefinition = schemaDefinition
-    <|> TypeDefinition <$> typeDefinition
-    <|> directiveDefinition
+    <|> typeSystemDefinitionWithDescription
     <?> "TypeSystemDefinition"
+  where
+    typeSystemDefinitionWithDescription = description
+        >>= liftA2 (<|>) typeDefinition' directiveDefinition
+    typeDefinition' description' = Full.TypeDefinition
+        <$> typeDefinition description'
 
-typeSystemExtension :: Parser TypeSystemExtension
-typeSystemExtension = SchemaExtension <$> schemaExtension
-    <|> TypeExtension <$> typeExtension
+typeSystemExtension :: Parser Full.TypeSystemExtension
+typeSystemExtension = Full.SchemaExtension <$> schemaExtension
+    <|> Full.TypeExtension <$> typeExtension
     <?> "TypeSystemExtension"
 
-directiveDefinition :: Parser TypeSystemDefinition
-directiveDefinition = DirectiveDefinition
-    <$> description
-    <* symbol "directive"
+directiveDefinition :: Full.Description -> Parser Full.TypeSystemDefinition
+directiveDefinition description' = Full.DirectiveDefinition description'
+    <$ symbol "directive"
     <* at
     <*> name
     <*> argumentsDefinition
@@ -63,11 +93,13 @@ directiveDefinition = DirectiveDefinition
 directiveLocations :: Parser (NonEmpty DirectiveLocation)
 directiveLocations = optional pipe
     *> directiveLocation `NonEmpty.sepBy1` pipe
+    <?> "DirectiveLocations"
 
 directiveLocation :: Parser DirectiveLocation
 directiveLocation
     = Directive.ExecutableDirectiveLocation <$> executableDirectiveLocation
     <|> Directive.TypeSystemDirectiveLocation <$> typeSystemDirectiveLocation
+    <?> "DirectiveLocation"
 
 executableDirectiveLocation :: Parser ExecutableDirectiveLocation
 executableDirectiveLocation = Directive.Query <$ symbol "QUERY"
@@ -77,6 +109,7 @@ executableDirectiveLocation = Directive.Query <$ symbol "QUERY"
     <|> Directive.FragmentDefinition <$ "FRAGMENT_DEFINITION"
     <|> Directive.FragmentSpread <$ "FRAGMENT_SPREAD"
     <|> Directive.InlineFragment <$ "INLINE_FRAGMENT"
+    <?> "ExecutableDirectiveLocation"
 
 typeSystemDirectiveLocation :: Parser TypeSystemDirectiveLocation
 typeSystemDirectiveLocation = Directive.Schema <$ symbol "SCHEMA"
@@ -90,17 +123,18 @@ typeSystemDirectiveLocation = Directive.Schema <$ symbol "SCHEMA"
     <|> Directive.EnumValue <$ symbol "ENUM_VALUE"
     <|> Directive.InputObject <$ symbol "INPUT_OBJECT"
     <|> Directive.InputFieldDefinition <$ symbol "INPUT_FIELD_DEFINITION"
+    <?> "TypeSystemDirectiveLocation"
 
-typeDefinition :: Parser TypeDefinition
-typeDefinition = scalarTypeDefinition
-    <|> objectTypeDefinition
-    <|> interfaceTypeDefinition
-    <|> unionTypeDefinition
-    <|> enumTypeDefinition
-    <|> inputObjectTypeDefinition
+typeDefinition :: Full.Description -> Parser Full.TypeDefinition
+typeDefinition description' = scalarTypeDefinition description'
+    <|> objectTypeDefinition description'
+    <|> interfaceTypeDefinition description'
+    <|> unionTypeDefinition description'
+    <|> enumTypeDefinition description'
+    <|> inputObjectTypeDefinition description'
     <?> "TypeDefinition"
 
-typeExtension :: Parser TypeExtension
+typeExtension :: Parser Full.TypeExtension
 typeExtension = scalarTypeExtension
     <|> objectTypeExtension
     <|> interfaceTypeExtension
@@ -109,149 +143,143 @@ typeExtension = scalarTypeExtension
     <|> inputObjectTypeExtension
     <?> "TypeExtension"
 
-scalarTypeDefinition :: Parser TypeDefinition
-scalarTypeDefinition = ScalarTypeDefinition
-    <$> description
-    <* symbol "scalar"
+scalarTypeDefinition :: Full.Description -> Parser Full.TypeDefinition
+scalarTypeDefinition description' = Full.ScalarTypeDefinition description'
+    <$ symbol "scalar"
     <*> name
     <*> directives
     <?> "ScalarTypeDefinition"
 
-scalarTypeExtension :: Parser TypeExtension
+scalarTypeExtension :: Parser Full.TypeExtension
 scalarTypeExtension = extend "scalar" "ScalarTypeExtension"
-    $ (ScalarTypeExtension <$> name <*> NonEmpty.some directive) :| []
+    $ (Full.ScalarTypeExtension <$> name <*> NonEmpty.some directive) :| []
 
-objectTypeDefinition :: Parser TypeDefinition
-objectTypeDefinition = ObjectTypeDefinition
-    <$> description
-    <* symbol "type"
+objectTypeDefinition :: Full.Description -> Parser Full.TypeDefinition
+objectTypeDefinition description' = Full.ObjectTypeDefinition description'
+    <$ symbol "type"
     <*> name
-    <*> option (ImplementsInterfaces []) (implementsInterfaces sepBy1)
+    <*> option (Full.ImplementsInterfaces []) (implementsInterfaces sepBy1)
     <*> directives
     <*> braces (many fieldDefinition)
     <?> "ObjectTypeDefinition"
 
-objectTypeExtension :: Parser TypeExtension
+objectTypeExtension :: Parser Full.TypeExtension
 objectTypeExtension = extend "type" "ObjectTypeExtension"
     $ fieldsDefinitionExtension :|
         [ directivesExtension
         , implementsInterfacesExtension
         ]
   where
-    fieldsDefinitionExtension = ObjectTypeFieldsDefinitionExtension
+    fieldsDefinitionExtension = Full.ObjectTypeFieldsDefinitionExtension
         <$> name
-        <*> option (ImplementsInterfaces []) (implementsInterfaces sepBy1)
+        <*> option (Full.ImplementsInterfaces []) (implementsInterfaces sepBy1)
         <*> directives
         <*> braces (NonEmpty.some fieldDefinition)
-    directivesExtension = ObjectTypeDirectivesExtension
+    directivesExtension = Full.ObjectTypeDirectivesExtension
         <$> name
-        <*> option (ImplementsInterfaces []) (implementsInterfaces sepBy1)
+        <*> option (Full.ImplementsInterfaces []) (implementsInterfaces sepBy1)
         <*> NonEmpty.some directive
-    implementsInterfacesExtension = ObjectTypeImplementsInterfacesExtension
+    implementsInterfacesExtension = Full.ObjectTypeImplementsInterfacesExtension
         <$> name
         <*> implementsInterfaces NonEmpty.sepBy1
 
-description :: Parser Description
-description = Description
-    <$> optional (string <|> blockString)
+description :: Parser Full.Description
+description = Full.Description
+    <$> optional stringValue
     <?> "Description"
 
-unionTypeDefinition :: Parser TypeDefinition
-unionTypeDefinition = UnionTypeDefinition
-    <$> description
-    <* symbol "union"
+unionTypeDefinition :: Full.Description -> Parser Full.TypeDefinition
+unionTypeDefinition description' = Full.UnionTypeDefinition description'
+    <$ symbol "union"
     <*> name
     <*> directives
-    <*> option (UnionMemberTypes []) (unionMemberTypes sepBy1)
+    <*> option (Full.UnionMemberTypes []) (unionMemberTypes sepBy1)
     <?> "UnionTypeDefinition"
 
-unionTypeExtension :: Parser TypeExtension
+unionTypeExtension :: Parser Full.TypeExtension
 unionTypeExtension = extend "union" "UnionTypeExtension"
     $ unionMemberTypesExtension :| [directivesExtension]
   where
-    unionMemberTypesExtension = UnionTypeUnionMemberTypesExtension
+    unionMemberTypesExtension = Full.UnionTypeUnionMemberTypesExtension
         <$> name
         <*> directives
         <*> unionMemberTypes NonEmpty.sepBy1
-    directivesExtension = UnionTypeDirectivesExtension
+    directivesExtension = Full.UnionTypeDirectivesExtension
         <$> name
         <*> NonEmpty.some directive
 
 unionMemberTypes ::
     Foldable t =>
-    (Parser Text -> Parser Text -> Parser (t NamedType)) ->
-    Parser (UnionMemberTypes t)
-unionMemberTypes sepBy' = UnionMemberTypes
+    (Parser Text -> Parser Text -> Parser (t Full.NamedType)) ->
+    Parser (Full.UnionMemberTypes t)
+unionMemberTypes sepBy' = Full.UnionMemberTypes
     <$ equals
     <* optional pipe
     <*> name `sepBy'` pipe
     <?> "UnionMemberTypes"
 
-interfaceTypeDefinition :: Parser TypeDefinition
-interfaceTypeDefinition = InterfaceTypeDefinition
-    <$> description
-    <* symbol "interface"
+interfaceTypeDefinition :: Full.Description -> Parser Full.TypeDefinition
+interfaceTypeDefinition description' = Full.InterfaceTypeDefinition description'
+    <$ symbol "interface"
     <*> name
     <*> directives
     <*> braces (many fieldDefinition)
     <?> "InterfaceTypeDefinition"
 
-interfaceTypeExtension :: Parser TypeExtension
+interfaceTypeExtension :: Parser Full.TypeExtension
 interfaceTypeExtension = extend "interface" "InterfaceTypeExtension"
     $ fieldsDefinitionExtension :| [directivesExtension]
   where
-    fieldsDefinitionExtension = InterfaceTypeFieldsDefinitionExtension
+    fieldsDefinitionExtension = Full.InterfaceTypeFieldsDefinitionExtension
         <$> name
         <*> directives
         <*> braces (NonEmpty.some fieldDefinition)
-    directivesExtension = InterfaceTypeDirectivesExtension
+    directivesExtension = Full.InterfaceTypeDirectivesExtension
         <$> name
         <*> NonEmpty.some directive
 
-enumTypeDefinition :: Parser TypeDefinition
-enumTypeDefinition = EnumTypeDefinition
-    <$> description
-    <* symbol "enum"
+enumTypeDefinition :: Full.Description -> Parser Full.TypeDefinition
+enumTypeDefinition description' = Full.EnumTypeDefinition description'
+    <$ symbol "enum"
     <*> name
     <*> directives
     <*> listOptIn braces enumValueDefinition
     <?> "EnumTypeDefinition"
 
-enumTypeExtension :: Parser TypeExtension
+enumTypeExtension :: Parser Full.TypeExtension
 enumTypeExtension = extend "enum" "EnumTypeExtension"
     $ enumValuesDefinitionExtension :| [directivesExtension]
   where
-    enumValuesDefinitionExtension = EnumTypeEnumValuesDefinitionExtension
+    enumValuesDefinitionExtension = Full.EnumTypeEnumValuesDefinitionExtension
         <$> name
         <*> directives
         <*> braces (NonEmpty.some enumValueDefinition)
-    directivesExtension = EnumTypeDirectivesExtension
+    directivesExtension = Full.EnumTypeDirectivesExtension
         <$> name
         <*> NonEmpty.some directive
 
-inputObjectTypeDefinition :: Parser TypeDefinition
-inputObjectTypeDefinition = InputObjectTypeDefinition
-    <$> description
-    <* symbol "input"
+inputObjectTypeDefinition :: Full.Description -> Parser Full.TypeDefinition
+inputObjectTypeDefinition description' = Full.InputObjectTypeDefinition description'
+    <$ symbol "input"
     <*> name
     <*> directives
     <*> listOptIn braces inputValueDefinition
     <?> "InputObjectTypeDefinition"
 
-inputObjectTypeExtension :: Parser TypeExtension
+inputObjectTypeExtension :: Parser Full.TypeExtension
 inputObjectTypeExtension = extend "input" "InputObjectTypeExtension"
     $ inputFieldsDefinitionExtension :| [directivesExtension]
   where
-    inputFieldsDefinitionExtension = InputObjectTypeInputFieldsDefinitionExtension
+    inputFieldsDefinitionExtension = Full.InputObjectTypeInputFieldsDefinitionExtension
         <$> name
         <*> directives
         <*> braces (NonEmpty.some inputValueDefinition)
-    directivesExtension = InputObjectTypeDirectivesExtension
+    directivesExtension = Full.InputObjectTypeDirectivesExtension
         <$> name
         <*> NonEmpty.some directive
 
-enumValueDefinition :: Parser EnumValueDefinition
-enumValueDefinition = EnumValueDefinition
+enumValueDefinition :: Parser Full.EnumValueDefinition
+enumValueDefinition = Full.EnumValueDefinition
     <$> description
     <*> enumValue
     <*> directives
@@ -259,16 +287,16 @@ enumValueDefinition = EnumValueDefinition
 
 implementsInterfaces ::
     Foldable t =>
-    (Parser Text -> Parser Text -> Parser (t NamedType)) ->
-    Parser (ImplementsInterfaces t)
-implementsInterfaces sepBy' = ImplementsInterfaces
+    (Parser Text -> Parser Text -> Parser (t Full.NamedType)) ->
+    Parser (Full.ImplementsInterfaces t)
+implementsInterfaces sepBy' = Full.ImplementsInterfaces
     <$ symbol "implements"
     <* optional amp
     <*> name `sepBy'` amp
     <?> "ImplementsInterfaces"
 
-inputValueDefinition :: Parser InputValueDefinition
-inputValueDefinition = InputValueDefinition
+inputValueDefinition :: Parser Full.InputValueDefinition
+inputValueDefinition = Full.InputValueDefinition
     <$> description
     <*> name
     <* colon
@@ -277,13 +305,13 @@ inputValueDefinition = InputValueDefinition
     <*> directives
     <?> "InputValueDefinition"
 
-argumentsDefinition :: Parser ArgumentsDefinition
-argumentsDefinition = ArgumentsDefinition
+argumentsDefinition :: Parser Full.ArgumentsDefinition
+argumentsDefinition = Full.ArgumentsDefinition
     <$> listOptIn parens inputValueDefinition
     <?> "ArgumentsDefinition"
 
-fieldDefinition :: Parser FieldDefinition
-fieldDefinition = FieldDefinition
+fieldDefinition :: Parser Full.FieldDefinition
+fieldDefinition = Full.FieldDefinition
     <$> description
     <*> name
     <*> argumentsDefinition
@@ -292,188 +320,227 @@ fieldDefinition = FieldDefinition
     <*> directives
     <?> "FieldDefinition"
 
-schemaDefinition :: Parser TypeSystemDefinition
-schemaDefinition = SchemaDefinition
+schemaDefinition :: Parser Full.TypeSystemDefinition
+schemaDefinition = Full.SchemaDefinition
     <$ symbol "schema"
     <*> directives
     <*> operationTypeDefinitions
     <?> "SchemaDefinition"
 
-operationTypeDefinitions :: Parser (NonEmpty OperationTypeDefinition)
+operationTypeDefinitions :: Parser (NonEmpty Full.OperationTypeDefinition)
 operationTypeDefinitions = braces $ NonEmpty.some operationTypeDefinition
 
-schemaExtension :: Parser SchemaExtension
+schemaExtension :: Parser Full.SchemaExtension
 schemaExtension = extend "schema" "SchemaExtension"
     $ schemaOperationExtension :| [directivesExtension]
   where
-    directivesExtension = SchemaDirectivesExtension
+    directivesExtension = Full.SchemaDirectivesExtension
         <$> NonEmpty.some directive
-    schemaOperationExtension = SchemaOperationExtension
+    schemaOperationExtension = Full.SchemaOperationExtension
         <$> directives
         <*> operationTypeDefinitions
 
-operationTypeDefinition :: Parser OperationTypeDefinition
-operationTypeDefinition = OperationTypeDefinition
+operationTypeDefinition :: Parser Full.OperationTypeDefinition
+operationTypeDefinition = Full.OperationTypeDefinition
     <$> operationType <* colon
     <*> name
     <?> "OperationTypeDefinition"
 
-operationDefinition :: Parser OperationDefinition
-operationDefinition = SelectionSet <$> selectionSet
+operationDefinition :: Parser Full.OperationDefinition
+operationDefinition = shorthand
     <|> operationDefinition'
-    <?> "operationDefinition error"
+    <?> "OperationDefinition"
   where
-    operationDefinition'
-        = OperationDefinition <$> operationType
-        <*> optional name
-        <*> variableDefinitions
-        <*> directives
-        <*> selectionSet
+    shorthand = do
+        location <- getLocation
+        selectionSet' <- selectionSet
+        pure $ Full.SelectionSet selectionSet' location
+    operationDefinition' = do
+        location <- getLocation
+        operationType' <- operationType
+        operationName <- optional name
+        variableDefinitions' <- variableDefinitions
+        directives' <- directives
+        selectionSet' <- selectionSet
+        pure $ Full.OperationDefinition
+            operationType'
+            operationName
+            variableDefinitions'
+            directives'
+            selectionSet'
+            location
 
-operationType :: Parser OperationType
-operationType = Query <$ symbol "query"
-    <|> Mutation <$ symbol "mutation"
-    -- <?> Keep default error message
+operationType :: Parser Full.OperationType
+operationType = Full.Query <$ symbol "query"
+    <|> Full.Mutation <$ symbol "mutation"
+    <|> Full.Subscription <$ symbol "subscription"
+    <?> "OperationType"
 
--- * SelectionSet
+selectionSet :: Parser Full.SelectionSet
+selectionSet = braces (NonEmpty.some selection) <?> "SelectionSet"
 
-selectionSet :: Parser SelectionSet
-selectionSet = braces $ NonEmpty.some selection
+selectionSetOpt :: Parser Full.SelectionSetOpt
+selectionSetOpt = listOptIn braces selection <?> "SelectionSet"
 
-selectionSetOpt :: Parser SelectionSetOpt
-selectionSetOpt = listOptIn braces selection
+selection :: Parser Full.Selection
+selection = Full.FieldSelection <$> field
+    <|> Full.FragmentSpreadSelection <$> try fragmentSpread
+    <|> Full.InlineFragmentSelection <$> inlineFragment
+    <?> "Selection"
 
-selection :: Parser Selection
-selection = field
-    <|> try fragmentSpread
-    <|> inlineFragment
-    <?> "selection error!"
+field :: Parser Full.Field
+field = label "Field" $ do
+    location <- getLocation
+    alias' <- optional alias
+    name' <- name
+    arguments' <- arguments
+    directives' <- directives
+    selectionSetOpt' <- selectionSetOpt
+    pure $ Full.Field alias' name' arguments' directives' selectionSetOpt' location
 
--- * Field
+alias :: Parser Full.Name
+alias = try (name <* colon) <?> "Alias"
 
-field :: Parser Selection
-field = Field
-    <$> optional alias
-    <*> name
-    <*> arguments
-    <*> directives
-    <*> selectionSetOpt
+arguments :: Parser [Full.Argument]
+arguments = listOptIn parens argument <?> "Arguments"
 
-alias :: Parser Alias
-alias = try $ name <* colon
+argument :: Parser Full.Argument
+argument = label "Argument" $ do
+    location <- getLocation
+    name' <- name
+    colon
+    value' <- valueNode value
+    pure $ Full.Argument name' value' location
 
--- * Arguments
+fragmentSpread :: Parser Full.FragmentSpread
+fragmentSpread = label "FragmentSpread" $ do
+    location <- getLocation
+    _ <- spread
+    fragmentName' <- fragmentName
+    directives' <- directives
+    pure $ Full.FragmentSpread fragmentName' directives' location
 
-arguments :: Parser [Argument]
-arguments = listOptIn parens argument
+inlineFragment :: Parser Full.InlineFragment
+inlineFragment = label "InlineFragment" $ do
+    location <- getLocation
+    _ <- spread
+    typeCondition' <- optional typeCondition
+    directives' <- directives
+    selectionSet' <- selectionSet
+    pure $ Full.InlineFragment typeCondition' directives' selectionSet' location
 
-argument :: Parser Argument
-argument = Argument <$> name <* colon <*> value
+fragmentDefinition :: Parser Full.FragmentDefinition
+fragmentDefinition =  label "FragmentDefinition" $ do
+    location <- getLocation
+    _ <- symbol "fragment"
+    fragmentName' <- name
+    typeCondition' <- typeCondition
+    directives' <- directives
+    selectionSet' <- selectionSet
+    pure $ Full.FragmentDefinition
+        fragmentName' typeCondition' directives' selectionSet' location
 
--- * Fragments
+fragmentName :: Parser Full.Name
+fragmentName = but (symbol "on") *> name <?> "FragmentName"
 
-fragmentSpread :: Parser Selection
-fragmentSpread = FragmentSpread
-    <$ spread
-    <*> fragmentName
-    <*> directives
+typeCondition :: Parser Full.TypeCondition
+typeCondition = symbol "on" *> name <?> "TypeCondition"
 
-inlineFragment :: Parser Selection
-inlineFragment = InlineFragment
-    <$ spread
-    <*> optional typeCondition
-    <*> directives
-    <*> selectionSet
+valueNode :: forall a. Parser a -> Parser (Full.Node a)
+valueNode valueParser = do
+    location <- getLocation
+    value' <- valueParser
+    pure $ Full.Node value' location
 
-fragmentDefinition :: Parser FragmentDefinition
-fragmentDefinition = FragmentDefinition
-                 <$  symbol "fragment"
-                 <*> name
-                 <*> typeCondition
-                 <*> directives
-                 <*> selectionSet
+value :: Parser Full.Value
+value = Full.Variable <$> variable
+    <|> Full.Float <$> try float
+    <|> Full.Int <$> integer
+    <|> Full.Boolean <$> booleanValue
+    <|> Full.Null <$  nullValue
+    <|> Full.String <$> stringValue
+    <|> Full.Enum <$> try enumValue
+    <|> Full.List <$> brackets (some value)
+    <|> Full.Object <$> braces (some $ objectField $ valueNode value)
+    <?> "Value"
 
-fragmentName :: Parser Name
-fragmentName = but (symbol "on") *> name
+constValue :: Parser Full.ConstValue
+constValue = Full.ConstFloat <$> try float
+    <|> Full.ConstInt <$> integer
+    <|> Full.ConstBoolean <$> booleanValue
+    <|> Full.ConstNull <$ nullValue
+    <|> Full.ConstString <$> stringValue
+    <|> Full.ConstEnum <$> try enumValue
+    <|> Full.ConstList <$> brackets (some constValue)
+    <|> Full.ConstObject <$> braces (some $ objectField $ valueNode constValue)
+    <?> "Value"
 
-typeCondition :: Parser TypeCondition
-typeCondition = symbol "on" *> name
+booleanValue :: Parser Bool
+booleanValue = True  <$ symbol "true"
+    <|> False <$ symbol "false"
+    <?> "BooleanValue"
 
--- * Input Values
+enumValue :: Parser Full.Name
+enumValue = but (symbol "true")
+    *> but (symbol "false")
+    *> but (symbol "null")
+    *> name
+    <?> "EnumValue"
 
-value :: Parser Value
-value = Variable <$> variable
-    <|> Float    <$> try float
-    <|> Int      <$> integer
-    <|> Boolean  <$> booleanValue
-    <|> Null     <$  symbol "null"
-    <|> String   <$> blockString
-    <|> String   <$> string
-    <|> Enum     <$> try enumValue
-    <|> List     <$> listValue
-    <|> Object   <$> objectValue
-    <?> "value error!"
-  where
-    booleanValue :: Parser Bool
-    booleanValue = True  <$ symbol "true"
-               <|> False <$ symbol "false"
+stringValue :: Parser Text
+stringValue = blockString <|> string <?> "StringValue"
 
-    listValue :: Parser [Value]
-    listValue = brackets $ some value
+nullValue :: Parser Text
+nullValue = symbol "null" <?> "NullValue"
 
-    objectValue :: Parser [ObjectField]
-    objectValue = braces $ some objectField
+objectField :: forall a. Parser (Full.Node a) -> Parser (Full.ObjectField a)
+objectField valueParser = label "ObjectField" $ do
+    location <- getLocation
+    fieldName <- name
+    colon
+    fieldValue <- valueParser
+    pure $ Full.ObjectField fieldName fieldValue location
 
-enumValue :: Parser Name
-enumValue = but (symbol "true") *> but (symbol "false") *> but (symbol "null") *> name
-
-objectField :: Parser ObjectField
-objectField = ObjectField <$> name <* colon <*> value
-
--- * Variables
-
-variableDefinitions :: Parser [VariableDefinition]
+variableDefinitions :: Parser [Full.VariableDefinition]
 variableDefinitions = listOptIn parens variableDefinition
+    <?> "VariableDefinitions"
 
-variableDefinition :: Parser VariableDefinition
-variableDefinition = VariableDefinition
-    <$> variable
-    <*  colon
-    <*> type'
-    <*> defaultValue
-    <?> "VariableDefinition"
+variableDefinition :: Parser Full.VariableDefinition
+variableDefinition = label "VariableDefinition" $ do
+    location <- getLocation
+    variableName <- variable
+    colon
+    variableType <- type'
+    variableValue <- defaultValue
+    pure $ Full.VariableDefinition variableName variableType variableValue location
 
-variable :: Parser Name
-variable = dollar *> name
+variable :: Parser Full.Name
+variable = dollar *> name <?> "Variable"
 
-defaultValue :: Parser (Maybe Value)
-defaultValue = optional (equals *> value) <?> "DefaultValue"
+defaultValue :: Parser (Maybe (Full.Node Full.ConstValue))
+defaultValue = optional (equals *> valueNode constValue) <?> "DefaultValue"
 
--- * Input Types
-
-type' :: Parser Type
-type' = try (TypeNonNull <$> nonNullType)
-    <|> TypeList <$> brackets type'
-    <|> TypeNamed <$> name
+type' :: Parser Full.Type
+type' = try (Full.TypeNonNull <$> nonNullType)
+    <|> Full.TypeList <$> brackets type'
+    <|> Full.TypeNamed <$> name
     <?> "Type"
 
-nonNullType :: Parser NonNullType
-nonNullType = NonNullTypeNamed <$> name <* bang
-          <|> NonNullTypeList  <$> brackets type'  <* bang
-          <?> "nonNullType error!"
+nonNullType :: Parser Full.NonNullType
+nonNullType = Full.NonNullTypeNamed <$> name <* bang
+    <|> Full.NonNullTypeList  <$> brackets type'  <* bang
+    <?> "NonNullType"
 
--- * Directives
+directives :: Parser [Full.Directive]
+directives = many directive <?> "Directives"
 
-directives :: Parser [Directive]
-directives = many directive
-
-directive :: Parser Directive
-directive = Directive
-    <$  at
-    <*> name
-    <*> arguments
-
--- * Internal
+directive :: Parser Full.Directive
+directive = label "Directive" $ do
+    location <- getLocation
+    at
+    directiveName <- name
+    directiveArguments <- arguments
+    pure $ Full.Directive directiveName directiveArguments location
 
 listOptIn :: (Parser [a] -> Parser [a]) -> Parser a -> Parser [a]
 listOptIn surround = option [] . surround . some

src/Language/GraphQL/Error.hs

@@ -1,25 +1,36 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE ExistentialQuantification #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 
 -- | Error handling.
 module Language.GraphQL.Error
-    ( parseError
-    , CollectErrsT
+    ( CollectErrsT
+    , Error(..)
+    , Path(..)
+    , Resolution(..)
+    , ResolverException(..)
+    , Response(..)
+    , ResponseEventStream
     , addErr
     , addErrMsg
+    , parseError
     , runCollectErrs
-    , runAppendErrs
     , singleError
     ) where
 
-import qualified Data.Aeson as Aeson
+import Conduit
+import Control.Exception (Exception(..))
+import Control.Monad.Trans.State (StateT, modify, runStateT)
+import Data.HashMap.Strict (HashMap)
+import Data.Sequence (Seq(..), (|>))
+import qualified Data.Sequence as Seq
 import Data.Text (Text)
-import Data.Void (Void)
-import Control.Monad.Trans.Class (lift)
-import Control.Monad.Trans.State ( StateT
-                                 , modify
-                                 , runStateT
-                                 )
+import qualified Data.Text as Text
+import Language.GraphQL.AST (Location(..), Name)
+import Language.GraphQL.Execute.Coerce
+import qualified Language.GraphQL.Type.Schema as Schema
+import Prelude hiding (null)
 import Text.Megaparsec
     ( ParseErrorBundle(..)
     , PosState(..)
@@ -30,59 +41,98 @@ import Text.Megaparsec
     , unPos
     )
 
+-- | Executor context.
+data Resolution m = Resolution
+    { errors :: Seq Error
+    , types :: HashMap Name (Schema.Type m)
+    }
+
 -- | Wraps a parse error into a list of errors.
-parseError :: Applicative f => ParseErrorBundle Text Void -> f Aeson.Value
+parseError :: (Applicative f, Serialize a)
+    => ParseErrorBundle Text Void
+    -> f (Response a)
 parseError ParseErrorBundle{..}  =
-    pure $ Aeson.object [("errors", Aeson.toJSON $ fst $ foldl go ([], bundlePosState) bundleErrors)]
+    pure $ Response null $ fst
+        $ foldl go (Seq.empty, bundlePosState) bundleErrors
   where
-    errorObject s SourcePos{..} = Aeson.object
-        [ ("message", Aeson.toJSON $ init $ parseErrorTextPretty s)
-        , ("line", Aeson.toJSON $ unPos sourceLine)
-        , ("column", Aeson.toJSON $ unPos sourceColumn)
-        ]
+    errorObject s SourcePos{..} = Error
+        { message = Text.pack $ init $ parseErrorTextPretty s
+        , locations = [Location (unPos' sourceLine) (unPos' sourceColumn)]
+        , path = []
+        }
+    unPos' = fromIntegral . unPos
     go (result, state) x =
         let (_, newState) = reachOffset (errorOffset x) state
             sourcePosition = pstateSourcePos newState
-         in (errorObject x sourcePosition : result, newState)
+         in (result |> errorObject x sourcePosition, newState)
 
 -- | A wrapper to pass error messages around.
-type CollectErrsT m = StateT [Aeson.Value] m
+type CollectErrsT m = StateT (Resolution m) m
 
 -- | Adds an error to the list of errors.
-addErr :: Monad m => Aeson.Value -> CollectErrsT m ()
-addErr v = modify (v :)
+addErr :: Monad m => Error -> CollectErrsT m ()
+addErr v = modify appender
+  where
+    appender :: Monad m => Resolution m -> Resolution m
+    appender resolution@Resolution{..} = resolution{ errors = errors |> v }
 
-makeErrorMessage :: Text -> Aeson.Value
-makeErrorMessage s = Aeson.object [("message", Aeson.toJSON s)]
+makeErrorMessage :: Text -> Error
+makeErrorMessage s = Error s [] []
 
 -- | Constructs a response object containing only the error with the given
---   message.
-singleError :: Text -> Aeson.Value
-singleError message = Aeson.object
-    [ ("errors", Aeson.toJSON [makeErrorMessage message])
-    ]
+-- message.
+singleError :: Serialize a => Text -> Response a
+singleError message = Response null $ Seq.singleton $ makeErrorMessage message
 
 -- | Convenience function for just wrapping an error message.
-addErrMsg :: Monad m => Text -> CollectErrsT m ()
-addErrMsg = addErr . makeErrorMessage
+addErrMsg :: (Monad m, Serialize a) => Text -> CollectErrsT m a
+addErrMsg errorMessage = (addErr . makeErrorMessage) errorMessage >> pure null
 
--- | Appends the given list of errors to the current list of errors.
-appendErrs :: Monad m => [Aeson.Value] -> CollectErrsT m ()
-appendErrs errs = modify (errs ++)
+-- | If an error can be associated to a particular field in the GraphQL result,
+-- it must contain an entry with the key path that details the path of the
+-- response field which experienced the error. This allows clients to identify
+-- whether a null result is intentional or caused by a runtime error.
+data Path
+    = Segment Text -- ^ Field name.
+    | Index Int -- ^ List index if a field returned a list.
+    deriving (Eq, Show)
+
+-- | @GraphQL@ error.
+data Error = Error
+    { message :: Text
+    , locations :: [Location]
+    , path :: [Path]
+    } deriving (Eq, Show)
+
+-- | The server\'s response describes the result of executing the requested
+-- operation if successful, and describes any errors encountered during the
+-- request.
+data Response a = Response
+    { data' :: a
+    , errors :: Seq Error
+    } deriving (Eq, Show)
+
+-- | Each event in the underlying Source Stream triggers execution of the
+-- subscription selection set. The results of the execution generate a Response
+-- Stream.
+type ResponseEventStream m a = ConduitT () (Response a) m ()
+
+-- | Only exceptions that inherit from 'ResolverException' a cought by the
+-- executor.
+data ResolverException = forall e. Exception e => ResolverException e
+
+instance Show ResolverException where
+    show (ResolverException e) = show e
+
+instance Exception ResolverException
 
 -- | Runs the given query computation, but collects the errors into an error
---   list, which is then sent back with the data.
-runCollectErrs :: Monad m => CollectErrsT m Aeson.Value -> m Aeson.Value
-runCollectErrs res = do
-    (dat, errs) <- runStateT res []
-    if null errs
-       then return $ Aeson.object [("data", dat)]
-       else return $ Aeson.object [("data", dat), ("errors", Aeson.toJSON $ reverse errs)]
-
--- | Runs the given computation, collecting the errors and appending them
---   to the previous list of errors.
-runAppendErrs :: Monad m => CollectErrsT m a -> CollectErrsT m a
-runAppendErrs f = do
-    (v, errs) <- lift $ runStateT f []
-    appendErrs errs
-    return v
+-- list, which is then sent back with the data.
+runCollectErrs :: (Monad m, Serialize a)
+    => HashMap Name (Schema.Type m)
+    -> CollectErrsT m a
+    -> m (Response a)
+runCollectErrs types' res = do
+    (dat, Resolution{..}) <- runStateT res
+        $ Resolution{ errors = Seq.empty, types = types' }
+    pure $ Response dat errors

src/Language/GraphQL/Execute.hs

@@ -3,37 +3,22 @@
 -- | This module provides functions to execute a @GraphQL@ request.
 module Language.GraphQL.Execute
     ( execute
-    , executeWithName
+    , module Language.GraphQL.Execute.Coerce
     ) where
 
-import qualified Data.Aeson as Aeson
-import Data.List.NonEmpty (NonEmpty(..))
-import qualified Data.List.NonEmpty as NonEmpty
+import Control.Monad.Catch (MonadCatch)
 import Data.HashMap.Strict (HashMap)
-import qualified Data.HashMap.Strict as HashMap
+import Data.Sequence (Seq(..))
 import Data.Text (Text)
-import qualified Data.Text as Text
-import Language.GraphQL.AST.Document
-import qualified Language.GraphQL.AST.Core as AST.Core
+import Language.GraphQL.AST.Document (Document, Name)
+import Language.GraphQL.Execute.Coerce
+import Language.GraphQL.Execute.Execution
 import qualified Language.GraphQL.Execute.Transform as Transform
+import qualified Language.GraphQL.Execute.Subscribe as Subscribe
 import Language.GraphQL.Error
-import qualified Language.GraphQL.Schema as Schema
-
--- | The substitution is applied to the document, and the resolvers are applied
--- to the resulting fields.
---
--- Returns the result of the query against the schema wrapped in a /data/
--- field, or errors wrapped in an /errors/ field.
-execute :: Monad m
-    => HashMap Text (NonEmpty (Schema.Resolver m)) -- ^ Resolvers.
-    -> Schema.Subs -- ^ Variable substitution function.
-    -> Document -- @GraphQL@ document.
-    -> m Aeson.Value
-execute schema subs doc =
-    maybe transformError (document schema Nothing)
-        $ Transform.document subs doc
-  where
-    transformError = return $ singleError "Schema transformation error."
+import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.Type.Out as Out
+import Language.GraphQL.Type.Schema
 
 -- | The substitution is applied to the document, and the resolvers are applied
 -- to the resulting fields. The operation name can be used if the document
@@ -41,46 +26,38 @@ execute schema subs doc =
 --
 -- Returns the result of the query against the schema wrapped in a /data/
 -- field, or errors wrapped in an /errors/ field.
-executeWithName :: Monad m
-    => HashMap Text (NonEmpty (Schema.Resolver m)) -- ^ Resolvers
-    -> Text -- ^ Operation name.
-    -> Schema.Subs -- ^ Variable substitution function.
-    -> Document -- ^ @GraphQL@ Document.
-    -> m Aeson.Value
-executeWithName schema name subs doc =
-    maybe transformError (document schema $ Just name)
-        $ Transform.document subs doc
-  where
-    transformError = return $ singleError "Schema transformation error."
+execute :: (MonadCatch m, VariableValue a, Serialize b)
+    => Schema m -- ^ Resolvers.
+    -> Maybe Text -- ^ Operation name.
+    -> HashMap Name a -- ^ Variable substitution function.
+    -> Document -- @GraphQL@ document.
+    -> m (Either (ResponseEventStream m b) (Response b))
+execute schema' operationName subs document =
+    case Transform.document schema' operationName subs document of
+        Left queryError -> pure
+            $ Right
+            $ singleError
+            $ Transform.queryError queryError
+        Right transformed -> executeRequest transformed
 
-document :: Monad m
-    => HashMap Text (NonEmpty (Schema.Resolver m))
-    -> Maybe Text
-    -> AST.Core.Document
-    -> m Aeson.Value
-document schema Nothing (op :| []) = operation schema op
-document schema (Just name) operations = case NonEmpty.dropWhile matchingName operations of
-    [] -> return $ singleError
-        $ Text.unwords ["Operation", name, "couldn't be found in the document."]
-    (op:_)  -> operation schema op
-  where
-    matchingName (AST.Core.Query (Just name') _) = name == name'
-    matchingName (AST.Core.Mutation (Just name') _) = name == name'
-    matchingName _ = False
-document _ _ _ = return $ singleError "Missing operation name."
+executeRequest :: (MonadCatch m, Serialize a)
+    => Transform.Document m
+    -> m (Either (ResponseEventStream m a) (Response a))
+executeRequest (Transform.Document types' rootObjectType operation)
+    | (Transform.Query _ fields) <- operation =
+        Right <$> executeOperation types' rootObjectType fields
+    | (Transform.Mutation _ fields) <- operation =
+        Right <$> executeOperation types' rootObjectType fields
+    | (Transform.Subscription _ fields) <- operation
+        = either (Right . singleError) Left
+        <$> Subscribe.subscribe types' rootObjectType fields
 
-operation :: Monad m
-    => HashMap Text (NonEmpty (Schema.Resolver m))
-    -> AST.Core.Operation
-    -> m Aeson.Value
-operation schema = schemaOperation
-  where
-    runResolver fields = runCollectErrs
-        . flip Schema.resolve fields
-        . Schema.resolversToMap
-    resolve fields queryType = maybe lookupError (runResolver fields)
-        $ HashMap.lookup queryType schema
-    lookupError = pure
-        $ singleError "Root operation type couldn't be found in the schema."
-    schemaOperation (AST.Core.Query _ fields) = resolve fields "Query"
-    schemaOperation (AST.Core.Mutation _ fields) = resolve fields "Mutation"
+-- This is actually executeMutation, but we don't distinguish between queries
+-- and mutations yet.
+executeOperation :: (MonadCatch m, Serialize a)
+    => HashMap Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> m (Response a)
+executeOperation types' objectType fields =
+    runCollectErrs types' $ executeSelectionSet Definition.Null objectType fields

src/Language/GraphQL/Execute/Coerce.hs

@@ -0,0 +1,234 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ViewPatterns #-}
+
+-- | Types and functions used for input and result coercion.
+module Language.GraphQL.Execute.Coerce
+    ( Output(..)
+    , Serialize(..)
+    , VariableValue(..)
+    , coerceInputLiteral
+    , matchFieldValues
+    ) where
+
+import qualified Data.Aeson as Aeson
+import Data.Int (Int32)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Map.Strict (Map)
+import Data.String (IsString(..))
+import Data.Text (Text)
+import qualified Data.Text.Lazy as Text.Lazy
+import qualified Data.Text.Lazy.Builder as Text.Builder
+import qualified Data.Text.Lazy.Builder.Int as Text.Builder
+import Data.Scientific (toBoundedInteger, toRealFloat)
+import Language.GraphQL.AST (Name)
+import qualified Language.GraphQL.Type as Type
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+
+-- | Since variables are passed separately from the query, in an independent
+-- format, they should be first coerced to the internal representation used by
+-- this implementation.
+class VariableValue a where
+    -- | Only a basic, format-specific, coercion must be done here. Type
+    -- correctness or nullability shouldn't be validated here, they will be
+    -- validated later. The type information is provided only as a hint.
+    --
+    -- For example @GraphQL@ prohibits the coercion from a 't:Float' to an
+    -- 't:Int', but @JSON@ doesn't have integers, so whole numbers should be
+    -- coerced to 't:Int` when receiving variables as a JSON object. The same
+    -- holds for 't:Enum'. There are formats that support enumerations, @JSON@
+    -- doesn't, so the type information is given and 'coerceVariableValue' can
+    -- check that an 't:Enum' is expected and treat the given value
+    -- appropriately. Even checking whether this value is a proper member of the
+    -- corresponding 't:Enum' type isn't required here, since this can be
+    -- checked independently.
+    --
+    -- Another example is an @ID@. @GraphQL@ explicitly allows to coerce
+    -- integers and strings to @ID@s, so if an @ID@ is received as an integer,
+    -- it can be left as is and will be coerced later.
+    --
+    -- If a value cannot be coerced without losing information, 'Nothing' should
+    -- be returned, the coercion will fail then and the query won't be executed.
+    coerceVariableValue
+        :: In.Type -- ^ Expected type (variable type given in the query).
+        -> a -- ^ Variable value being coerced.
+        -> Maybe Type.Value -- ^ Coerced value on success, 'Nothing' otherwise.
+
+instance VariableValue Aeson.Value where
+    coerceVariableValue _ Aeson.Null = Just Type.Null
+    coerceVariableValue (In.ScalarBaseType scalarType) value
+        | (Aeson.String stringValue) <- value = Just $ Type.String stringValue
+        | (Aeson.Bool booleanValue) <- value = Just $ Type.Boolean booleanValue
+        | (Aeson.Number numberValue) <- value
+        , (Type.ScalarType "Float" _) <- scalarType =
+            Just $ Type.Float $ toRealFloat numberValue
+        | (Aeson.Number numberValue) <- value = -- ID or Int
+            Type.Int <$> toBoundedInteger numberValue
+    coerceVariableValue (In.EnumBaseType _) (Aeson.String stringValue) =
+        Just $ Type.Enum stringValue
+    coerceVariableValue (In.InputObjectBaseType objectType) value
+        | (Aeson.Object objectValue) <- value = do
+            let (In.InputObjectType _ _ inputFields) = objectType
+            (newObjectValue, resultMap) <- foldWithKey objectValue inputFields
+            if HashMap.null newObjectValue
+                then Just $ Type.Object resultMap
+                else Nothing
+      where
+        foldWithKey objectValue = HashMap.foldrWithKey matchFieldValues'
+            $ Just (objectValue, HashMap.empty)
+        matchFieldValues' _ _ Nothing = Nothing
+        matchFieldValues' fieldName inputField (Just (objectValue, resultMap)) =
+            let (In.InputField _ fieldType _) = inputField
+                insert = flip (HashMap.insert fieldName) resultMap
+                newObjectValue = HashMap.delete fieldName objectValue
+             in case HashMap.lookup fieldName objectValue of
+                    Just variableValue -> do
+                        coerced <- coerceVariableValue fieldType variableValue
+                        pure (newObjectValue, insert coerced)
+                    Nothing -> Just (objectValue, resultMap)
+    coerceVariableValue (In.ListBaseType listType) value
+        | (Aeson.Array arrayValue) <- value =
+            Type.List <$> foldr foldVector (Just []) arrayValue
+        | otherwise = coerceVariableValue listType value
+      where
+        foldVector _ Nothing = Nothing
+        foldVector variableValue (Just list) = do
+            coerced <- coerceVariableValue listType variableValue
+            pure $ coerced : list 
+    coerceVariableValue _ _ = Nothing
+
+-- | Looks up a value by name in the given map, coerces it and inserts into the
+-- result map. If the coercion fails, returns 'Nothing'. If the value isn't
+-- given, but a default value is known, inserts the default value into the
+-- result map. Otherwise it fails with 'Nothing' if the Input Type is a
+-- Non-Nullable type, or returns the unchanged, original map.
+matchFieldValues :: forall a
+    . (In.Type -> a -> Maybe Type.Value)
+    -> HashMap Name a
+    -> Name
+    -> In.Type
+    -> Maybe Type.Value
+    -> Maybe (HashMap Name Type.Value)
+    -> Maybe (HashMap Name Type.Value)
+matchFieldValues coerce values' fieldName type' defaultValue resultMap =
+    case HashMap.lookup fieldName values' of
+        Just variableValue -> coerceRuntimeValue $ coerce type' variableValue
+        Nothing
+            | Just value <- defaultValue ->
+                HashMap.insert fieldName value <$> resultMap
+            | Nothing <- defaultValue
+            , In.isNonNullType type' -> Nothing
+            | otherwise -> resultMap
+  where
+    coerceRuntimeValue (Just Type.Null)
+        | In.isNonNullType type' = Nothing
+    coerceRuntimeValue coercedValue =
+        HashMap.insert fieldName <$> coercedValue <*> resultMap
+
+-- | Coerces operation arguments according to the input coercion rules for the
+-- corresponding types.
+coerceInputLiteral :: In.Type -> Type.Value -> Maybe Type.Value
+coerceInputLiteral (In.isNonNullType -> False) Type.Null = Just Type.Null
+coerceInputLiteral (In.ScalarBaseType type') value
+    | (Type.String stringValue) <- value
+    , (Type.ScalarType "String" _) <- type' = Just $ Type.String stringValue
+    | (Type.Boolean booleanValue) <- value
+    , (Type.ScalarType "Boolean" _) <- type' = Just $ Type.Boolean booleanValue
+    | (Type.Int intValue) <- value
+    , (Type.ScalarType "Int" _) <- type' = Just $ Type.Int intValue
+    | (Type.Float floatValue) <- value
+    , (Type.ScalarType "Float" _) <- type' = Just $ Type.Float floatValue
+    | (Type.Int intValue) <- value
+    , (Type.ScalarType "Float" _) <- type' =
+        Just $ Type.Float $ fromIntegral intValue
+    | (Type.String stringValue) <- value
+    , (Type.ScalarType "ID" _) <- type' = Just $ Type.String stringValue
+    | (Type.Int intValue) <- value
+    , (Type.ScalarType "ID" _) <- type' = Just $ decimal intValue
+  where
+    decimal = Type.String
+        . Text.Lazy.toStrict
+        . Text.Builder.toLazyText
+        . Text.Builder.decimal
+coerceInputLiteral (In.EnumBaseType type') (Type.Enum enumValue)
+    | member enumValue type' = Just $ Type.Enum enumValue
+  where
+    member value (Type.EnumType _ _ members) = HashMap.member value members
+coerceInputLiteral (In.InputObjectBaseType type') (Type.Object values) = 
+    let (In.InputObjectType _ _ inputFields) = type'
+     in Type.Object
+            <$> HashMap.foldrWithKey (matchFieldValues' values) (Just HashMap.empty) inputFields
+  where
+    matchFieldValues' values' fieldName (In.InputField _ inputFieldType defaultValue) =
+        matchFieldValues coerceInputLiteral values' fieldName inputFieldType defaultValue
+coerceInputLiteral (In.ListBaseType listType) (Type.List list) =
+    Type.List <$> traverse (coerceInputLiteral listType) list
+coerceInputLiteral (In.ListBaseType listType) singleton =
+    wrapSingleton listType singleton
+  where
+      wrapSingleton (In.ListBaseType listType') singleton' =
+          Type.List <$> sequence [wrapSingleton listType' singleton']
+      wrapSingleton listType' singleton' =
+          Type.List <$> sequence [coerceInputLiteral listType' singleton']
+coerceInputLiteral _ _ = Nothing
+
+-- | 'Serialize' describes how a @GraphQL@ value should be serialized.
+class Serialize a where
+    -- | Serializes a @GraphQL@ value according to the given serialization
+    -- format.
+    --
+    -- Type infomration is given as a hint, e.g. if you need to know what type
+    -- is being serialized to serialize it properly. Don't do any validation for
+    -- @GraphQL@ built-in types here.
+    --
+    -- If the value cannot be serialized without losing information, return
+    -- 'Nothing' — it will cause a field error.
+    serialize :: forall m
+        . Out.Type m -- ^ Expected output type.
+        -> Output a -- ^ The value to be serialized.
+        -> Maybe a -- ^ Serialized value on success or 'Nothing'.
+    -- | __null__ representation in the given serialization format.
+    null :: a
+
+-- | Intermediate type used to serialize a @GraphQL@ value.
+--
+-- The serialization is done during the execution, and 'Output' contains
+-- already serialized data (in 'List' and 'Object') as well as the new layer
+-- that has to be serialized in the current step. So 'Output' is parameterized
+-- by the serialization format.
+data Output a
+    = Int Int32
+    | Float Double
+    | String Text
+    | Boolean Bool
+    | Enum Name
+    | List [a]
+    | Object (Map Name a)
+    deriving (Eq, Show)
+
+instance forall a. IsString (Output a) where
+    fromString = String . fromString
+
+instance Serialize Aeson.Value where
+    serialize (Out.ScalarBaseType scalarType) value
+        | Type.ScalarType "Int" _ <- scalarType
+        , Int int <- value = Just $ Aeson.toJSON int
+        | Type.ScalarType "Float" _ <- scalarType
+        , Float float <- value = Just $ Aeson.toJSON float
+        | Type.ScalarType "String" _ <- scalarType
+        , String string <- value = Just $ Aeson.String string
+        | Type.ScalarType "ID" _ <- scalarType
+        , String string <- value = Just $ Aeson.String string
+        | Type.ScalarType "Boolean" _ <- scalarType
+        , Boolean boolean <- value = Just $ Aeson.Bool boolean
+    serialize _ (Enum enum) = Just $ Aeson.String enum
+    serialize _ (List list) = Just $ Aeson.toJSON list
+    serialize _ (Object object) = Just $ Aeson.toJSON object
+    serialize _ _ = Nothing
+    null = Aeson.Null

src/Language/GraphQL/Execute/Execution.hs

@@ -0,0 +1,216 @@
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ViewPatterns #-}
+
+module Language.GraphQL.Execute.Execution
+    ( coerceArgumentValues
+    , collectFields
+    , executeSelectionSet
+    ) where
+
+import Control.Monad.Catch (Exception(..), MonadCatch(..))
+import Control.Monad.Trans.Class (lift)
+import Control.Monad.Trans.Reader (runReaderT)
+import Control.Monad.Trans.State (gets)
+import Data.List.NonEmpty (NonEmpty(..))
+import Data.Map.Strict (Map)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Map.Strict as Map
+import Data.Maybe (fromMaybe)
+import Data.Sequence (Seq(..))
+import qualified Data.Text as Text
+import Language.GraphQL.AST (Name)
+import Language.GraphQL.Error
+import Language.GraphQL.Execute.Coerce
+import qualified Language.GraphQL.Execute.Transform as Transform
+import qualified Language.GraphQL.Type as Type
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+import qualified Language.GraphQL.Type.Internal as Internal
+import Prelude hiding (null)
+
+resolveFieldValue :: MonadCatch m
+    => Type.Value
+    -> Type.Subs
+    -> Type.Resolve m
+    -> CollectErrsT m Type.Value
+resolveFieldValue result args resolver =
+    catch (lift $ runReaderT resolver context) handleFieldError
+  where
+    handleFieldError :: MonadCatch m
+        => ResolverException
+        -> CollectErrsT m Type.Value
+    handleFieldError e =
+        addErr (Error (Text.pack $ displayException e) [] []) >> pure Type.Null
+    context = Type.Context
+        { Type.arguments = Type.Arguments args
+        , Type.values = result
+        }
+
+collectFields :: Monad m
+    => Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> Map Name (NonEmpty (Transform.Field m))
+collectFields objectType = foldl forEach Map.empty
+  where
+    forEach groupedFields (Transform.SelectionField field) =
+        let responseKey = aliasOrName field
+         in Map.insertWith (<>) responseKey (field :| []) groupedFields
+    forEach groupedFields (Transform.SelectionFragment selectionFragment)
+        | Transform.Fragment fragmentType fragmentSelectionSet <- selectionFragment
+        , Internal.doesFragmentTypeApply fragmentType objectType =
+            let fragmentGroupedFieldSet = collectFields objectType fragmentSelectionSet
+             in Map.unionWith (<>) groupedFields fragmentGroupedFieldSet
+        | otherwise = groupedFields
+
+aliasOrName :: forall m. Transform.Field m -> Name
+aliasOrName (Transform.Field alias name _ _) = fromMaybe name alias
+
+resolveAbstractType :: Monad m
+    => Internal.AbstractType m
+    -> Type.Subs
+    -> CollectErrsT m (Maybe (Out.ObjectType m))
+resolveAbstractType abstractType values'
+    | Just (Type.String typeName) <- HashMap.lookup "__typename" values' = do
+        types' <- gets types
+        case HashMap.lookup typeName types' of
+            Just (Internal.ObjectType objectType) ->
+                if Internal.instanceOf objectType abstractType
+                    then pure $ Just objectType
+                    else pure Nothing
+            _ -> pure Nothing
+    | otherwise = pure Nothing
+
+executeField :: (MonadCatch m, Serialize a)
+    => Out.Resolver m
+    -> Type.Value
+    -> NonEmpty (Transform.Field m)
+    -> CollectErrsT m a
+executeField fieldResolver prev fields
+    | Out.ValueResolver fieldDefinition resolver <- fieldResolver =
+        executeField' fieldDefinition resolver
+    | Out.EventStreamResolver fieldDefinition resolver _ <- fieldResolver =
+        executeField' fieldDefinition resolver
+  where
+    executeField' fieldDefinition resolver = do
+        let Out.Field _ fieldType argumentDefinitions = fieldDefinition
+        let (Transform.Field _ _ arguments' _ :| []) = fields
+        case coerceArgumentValues argumentDefinitions arguments' of
+            Nothing -> addErrMsg "Argument coercing failed."
+            Just argumentValues -> do
+                answer <- resolveFieldValue prev argumentValues resolver
+                completeValue fieldType fields answer
+
+completeValue :: (MonadCatch m, Serialize a)
+    => Out.Type m
+    -> NonEmpty (Transform.Field m)
+    -> Type.Value
+    -> CollectErrsT m a
+completeValue (Out.isNonNullType -> False) _ Type.Null = pure null
+completeValue outputType@(Out.ListBaseType listType) fields (Type.List list)
+    = traverse (completeValue listType fields) list
+    >>= coerceResult outputType . List
+completeValue outputType@(Out.ScalarBaseType _) _ (Type.Int int) =
+    coerceResult outputType $ Int int
+completeValue outputType@(Out.ScalarBaseType _) _ (Type.Boolean boolean) =
+    coerceResult outputType $ Boolean boolean
+completeValue outputType@(Out.ScalarBaseType _) _ (Type.Float float) =
+    coerceResult outputType $ Float float
+completeValue outputType@(Out.ScalarBaseType _) _ (Type.String string) =
+    coerceResult outputType $ String string
+completeValue outputType@(Out.EnumBaseType enumType) _ (Type.Enum enum) =
+    let Type.EnumType _ _ enumMembers = enumType
+     in if HashMap.member enum enumMembers
+        then coerceResult outputType $ Enum enum
+        else addErrMsg "Enum value completion failed."
+completeValue (Out.ObjectBaseType objectType) fields result =
+    executeSelectionSet result objectType $ mergeSelectionSets fields
+completeValue (Out.InterfaceBaseType interfaceType) fields result
+    | Type.Object objectMap <- result = do
+        let abstractType = Internal.AbstractInterfaceType interfaceType
+        concreteType <- resolveAbstractType abstractType objectMap
+        case concreteType of
+            Just objectType -> executeSelectionSet result objectType
+                $ mergeSelectionSets fields
+            Nothing -> addErrMsg "Interface value completion failed."
+completeValue (Out.UnionBaseType unionType) fields result
+    | Type.Object objectMap <- result = do
+        let abstractType = Internal.AbstractUnionType unionType
+        concreteType <- resolveAbstractType abstractType objectMap
+        case concreteType of
+            Just objectType -> executeSelectionSet result objectType
+                $ mergeSelectionSets fields
+            Nothing -> addErrMsg "Union value completion failed."
+completeValue _ _ _ = addErrMsg "Value completion failed."
+
+mergeSelectionSets :: MonadCatch m
+    => NonEmpty (Transform.Field m)
+    -> Seq (Transform.Selection m)
+mergeSelectionSets = foldr forEach mempty
+  where
+    forEach (Transform.Field _ _ _ fieldSelectionSet) selectionSet =
+        selectionSet <> fieldSelectionSet
+
+coerceResult :: (MonadCatch m, Serialize a)
+    => Out.Type m
+    -> Output a
+    -> CollectErrsT m a
+coerceResult outputType result
+    | Just serialized <- serialize outputType result = pure serialized
+    | otherwise = addErrMsg "Result coercion failed."
+
+-- | Takes an 'Out.ObjectType' and a list of 'Transform.Selection's and applies
+-- each field to each 'Transform.Selection'. Resolves into a value containing
+-- the resolved 'Transform.Selection', or a null value and error information.
+executeSelectionSet :: (MonadCatch m, Serialize a)
+    => Type.Value
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> CollectErrsT m a
+executeSelectionSet result objectType@(Out.ObjectType _ _ _ resolvers) selectionSet = do
+    let fields = collectFields objectType selectionSet
+    resolvedValues <- Map.traverseMaybeWithKey forEach fields
+    coerceResult (Out.NonNullObjectType objectType) $ Object resolvedValues
+  where
+    forEach _ fields@(field :| _) =
+        let Transform.Field _ name _ _ = field
+         in traverse (tryResolver fields) $ lookupResolver name
+    lookupResolver = flip HashMap.lookup resolvers
+    tryResolver fields resolver =
+        executeField resolver result fields >>= lift . pure
+
+coerceArgumentValues
+    :: HashMap Name In.Argument
+    -> HashMap Name Transform.Input
+    -> Maybe Type.Subs
+coerceArgumentValues argumentDefinitions argumentValues =
+    HashMap.foldrWithKey forEach (pure mempty) argumentDefinitions
+  where
+    forEach variableName (In.Argument _ variableType defaultValue) =
+        matchFieldValues coerceArgumentValue argumentValues variableName variableType defaultValue
+    coerceArgumentValue inputType (Transform.Int integer) =
+        coerceInputLiteral inputType (Type.Int integer)
+    coerceArgumentValue inputType (Transform.Boolean boolean) =
+        coerceInputLiteral inputType (Type.Boolean boolean)
+    coerceArgumentValue inputType (Transform.String string) =
+        coerceInputLiteral inputType (Type.String string)
+    coerceArgumentValue inputType (Transform.Float float) =
+        coerceInputLiteral inputType (Type.Float float)
+    coerceArgumentValue inputType (Transform.Enum enum) =
+        coerceInputLiteral inputType (Type.Enum enum)
+    coerceArgumentValue inputType Transform.Null
+        | In.isNonNullType inputType = Nothing
+        | otherwise = coerceInputLiteral inputType Type.Null
+    coerceArgumentValue (In.ListBaseType inputType) (Transform.List list) =
+        let coerceItem = coerceInputLiteral inputType
+         in Type.List <$> traverse coerceItem list
+    coerceArgumentValue (In.InputObjectBaseType inputType) (Transform.Object object)
+        | In.InputObjectType _ _ inputFields <- inputType = 
+            let go = forEachField object
+                resultMap = HashMap.foldrWithKey go (pure mempty) inputFields
+             in Type.Object <$> resultMap
+    coerceArgumentValue _ (Transform.Variable variable) = pure variable
+    coerceArgumentValue _ _ = Nothing
+    forEachField object variableName (In.InputField _ variableType defaultValue) =
+        matchFieldValues coerceArgumentValue object variableName variableType defaultValue

src/Language/GraphQL/Execute/Subscribe.hs

@@ -0,0 +1,97 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE OverloadedStrings #-}
+module Language.GraphQL.Execute.Subscribe
+    ( subscribe
+    ) where
+
+import Conduit
+import Control.Monad.Catch (Exception(..), MonadCatch(..))
+import Control.Monad.Trans.Reader (ReaderT(..), runReaderT)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Map.Strict as Map
+import qualified Data.List.NonEmpty as NonEmpty
+import Data.Sequence (Seq(..))
+import Data.Text (Text)
+import qualified Data.Text as Text
+import Language.GraphQL.AST (Name)
+import Language.GraphQL.Execute.Coerce
+import Language.GraphQL.Execute.Execution
+import qualified Language.GraphQL.Execute.Transform as Transform
+import Language.GraphQL.Error
+import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.Type as Type
+import qualified Language.GraphQL.Type.Out as Out
+import Language.GraphQL.Type.Schema
+
+-- This is actually executeMutation, but we don't distinguish between queries
+-- and mutations yet.
+subscribe :: (MonadCatch m, Serialize a)
+    => HashMap Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> m (Either Text (ResponseEventStream m a))
+subscribe types' objectType fields = do
+    sourceStream <- createSourceEventStream types' objectType fields
+    traverse (mapSourceToResponseEvent types' objectType fields) sourceStream
+
+mapSourceToResponseEvent :: (MonadCatch m, Serialize a)
+    => HashMap Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> Out.SourceEventStream m
+    -> m (ResponseEventStream m a)
+mapSourceToResponseEvent types' subscriptionType fields sourceStream = pure
+    $ sourceStream
+    .| mapMC (executeSubscriptionEvent types' subscriptionType fields)
+
+createSourceEventStream :: MonadCatch m
+    => HashMap Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> m (Either Text (Out.SourceEventStream m))
+createSourceEventStream _types subscriptionType@(Out.ObjectType _ _ _ fieldTypes) fields
+    | [fieldGroup] <- Map.elems groupedFieldSet
+    , Transform.Field _ fieldName arguments' _ <- NonEmpty.head fieldGroup
+    , resolverT <- fieldTypes HashMap.! fieldName
+    , Out.EventStreamResolver fieldDefinition _ resolver <- resolverT
+    , Out.Field _ _fieldType argumentDefinitions <- fieldDefinition =
+        case coerceArgumentValues argumentDefinitions arguments' of
+            Nothing -> pure $ Left "Argument coercion failed."
+            Just argumentValues ->
+                resolveFieldEventStream Type.Null argumentValues resolver
+    | otherwise = pure $ Left "Subscription contains more than one field."
+  where
+    groupedFieldSet = collectFields subscriptionType fields
+
+resolveFieldEventStream :: MonadCatch m
+    => Type.Value
+    -> Type.Subs
+    -> Out.Subscribe m
+    -> m (Either Text (Out.SourceEventStream m))
+resolveFieldEventStream result args resolver =
+    catch (Right <$> runReaderT resolver context) handleEventStreamError
+  where
+    handleEventStreamError :: MonadCatch m
+        => ResolverException
+        -> m (Either Text (Out.SourceEventStream m))
+    handleEventStreamError = pure . Left . Text.pack . displayException
+    context = Type.Context
+        { Type.arguments = Type.Arguments args
+        , Type.values = result
+        }
+
+-- This is actually executeMutation, but we don't distinguish between queries
+-- and mutations yet.
+executeSubscriptionEvent :: (MonadCatch m, Serialize a)
+    => HashMap Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> Definition.Value
+    -> m (Response a)
+executeSubscriptionEvent types' objectType fields initialValue =
+    runCollectErrs types' $ executeSelectionSet initialValue objectType fields

src/Language/GraphQL/Execute/Transform.hs

@@ -1,125 +1,347 @@
 {-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE TupleSections #-}
 
--- | After the document is parsed, before getting executed the AST is
---   transformed into a similar, simpler AST. This module is responsible for
---   this transformation.
+-- | After the document is parsed, before getting executed, the AST is
+-- transformed into a similar, simpler AST. Performed transformations include:
+--
+--   * Replacing variables with their values.
+--   * Inlining fragments. Some fragments can be completely eliminated and
+--   replaced by the selection set they represent. Invalid (recursive and
+--   non-existing) fragments are skipped. The most fragments are inlined, so the
+--   executor doesn't have to perform additional lookups later.
+--   * Evaluating directives (@\@include@ and @\@skip@).
+--
+-- This module is also responsible for smaller rewrites that touch only parts of
+-- the original AST.
 module Language.GraphQL.Execute.Transform
-    ( document
+    ( Document(..)
+    , Field(..)
+    , Fragment(..)
+    , Input(..)
+    , Operation(..)
+    , QueryError(..)
+    , Selection(..)
+    , document
+    , queryError
     ) where
 
-import Control.Arrow (first)
 import Control.Monad (foldM, unless)
 import Control.Monad.Trans.Class (lift)
-import Control.Monad.Trans.Reader (ReaderT, asks, runReaderT)
-import Control.Monad.Trans.State (StateT, evalStateT, gets, modify)
+import Control.Monad.Trans.State (State, evalStateT, gets, modify)
+import Data.Foldable (find)
+import Data.Functor.Identity (Identity(..))
 import Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as HashMap
+import Data.Int (Int32)
+import Data.Maybe (fromMaybe)
+import Data.List.NonEmpty (NonEmpty(..))
 import qualified Data.List.NonEmpty as NonEmpty
 import Data.Sequence (Seq, (<|), (><))
+import Data.Text (Text)
+import qualified Data.Text as Text
 import qualified Language.GraphQL.AST as Full
-import qualified Language.GraphQL.AST.Core as Core
-import Language.GraphQL.AST.Document (Definition(..), Document)
-import qualified Language.GraphQL.Schema as Schema
-import qualified Language.GraphQL.Type.Directive as Directive
+import Language.GraphQL.AST (Name)
+import qualified Language.GraphQL.Execute.Coerce as Coerce
+import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.Type as Type
+import qualified Language.GraphQL.Type.Internal as Type
+import qualified Language.GraphQL.Type.Out as Out
+import qualified Language.GraphQL.Type.Schema as Schema
 
--- | Associates a fragment name with a list of 'Core.Field's.
-data Replacement = Replacement
-    { fragments :: HashMap Core.Name Core.Fragment
-    , fragmentDefinitions :: HashMap Full.Name Full.FragmentDefinition
+-- | Associates a fragment name with a list of 'Field's.
+data Replacement m = Replacement
+    { fragments :: HashMap Full.Name (Fragment m)
+    , fragmentDefinitions :: FragmentDefinitions
+    , variableValues :: Type.Subs
+    , types :: HashMap Full.Name (Schema.Type m)
     }
 
-type TransformT a = StateT Replacement (ReaderT Schema.Subs Maybe) a
+type FragmentDefinitions = HashMap Full.Name Full.FragmentDefinition
 
-liftJust :: forall a. a -> TransformT a
-liftJust = lift . lift . Just
+-- | Represents fragments and inline fragments.
+data Fragment m
+    = Fragment (Type.CompositeType m) (Seq (Selection m))
+
+-- | Single selection element.
+data Selection m
+    = SelectionFragment (Fragment m)
+    | SelectionField (Field m)
+
+-- | GraphQL has 3 operation types: queries, mutations and subscribtions.
+--
+-- Currently only queries and mutations are supported.
+data Operation m
+    = Query (Maybe Text) (Seq (Selection m))
+    | Mutation (Maybe Text) (Seq (Selection m))
+    | Subscription (Maybe Text) (Seq (Selection m))
+
+-- | Single GraphQL field.
+data Field m = Field
+    (Maybe Full.Name) Full.Name (HashMap Full.Name Input) (Seq (Selection m))
+
+-- | Contains the operation to be executed along with its root type.
+data Document m = Document
+    (HashMap Full.Name (Schema.Type m)) (Out.ObjectType m) (Operation m)
+
+data OperationDefinition = OperationDefinition
+    Full.OperationType
+    (Maybe Full.Name)
+    [Full.VariableDefinition]
+    [Full.Directive]
+    Full.SelectionSet
+
+-- | Query error types.
+data QueryError
+    = OperationNotFound Text
+    | OperationNameRequired
+    | CoercionError
+    | TransformationError
+    | EmptyDocument
+    | UnsupportedRootOperation
+
+data Input
+    = Int Int32
+    | Float Double
+    | String Text
+    | Boolean Bool
+    | Null
+    | Enum Name
+    | List [Type.Value]
+    | Object (HashMap Name Input)
+    | Variable Type.Value
+    deriving (Eq, Show)
+
+queryError :: QueryError -> Text
+queryError (OperationNotFound operationName) = Text.unwords
+    ["Operation", operationName, "couldn't be found in the document."]
+queryError OperationNameRequired = "Missing operation name."
+queryError CoercionError = "Coercion error."
+queryError TransformationError = "Schema transformation error."
+queryError EmptyDocument =
+    "The document doesn't contain any executable operations."
+queryError UnsupportedRootOperation =
+    "Root operation type couldn't be found in the schema."
+
+getOperation
+    :: Maybe Full.Name
+    -> NonEmpty OperationDefinition
+    -> Either QueryError OperationDefinition
+getOperation Nothing (operation' :| []) = pure operation'
+getOperation Nothing _ = Left OperationNameRequired
+getOperation (Just operationName) operations
+    | Just operation' <- find matchingName operations = pure operation'
+    | otherwise = Left $ OperationNotFound operationName
+  where
+    matchingName (OperationDefinition _ name _ _ _) =
+        name == Just operationName
+
+coerceVariableValues :: Coerce.VariableValue a
+    => forall m
+    . HashMap Full.Name (Schema.Type m)
+    -> OperationDefinition
+    -> HashMap.HashMap Full.Name a
+    -> Either QueryError Type.Subs
+coerceVariableValues types operationDefinition variableValues =
+    let OperationDefinition _ _ variableDefinitions _ _ = operationDefinition
+     in maybe (Left CoercionError) Right
+        $ foldr forEach (Just HashMap.empty) variableDefinitions
+  where
+    forEach variableDefinition coercedValues = do
+        let Full.VariableDefinition variableName variableTypeName defaultValue _ =
+                variableDefinition
+        let defaultValue' = constValue . Full.node <$> defaultValue
+        variableType <- Type.lookupInputType variableTypeName types
+
+        Coerce.matchFieldValues
+            coerceVariableValue'
+            variableValues
+            variableName
+            variableType
+            defaultValue'
+            coercedValues
+    coerceVariableValue' variableType value'
+        = Coerce.coerceVariableValue variableType value'
+        >>= Coerce.coerceInputLiteral variableType
+
+constValue :: Full.ConstValue -> Type.Value
+constValue (Full.ConstInt i) = Type.Int i
+constValue (Full.ConstFloat f) = Type.Float f
+constValue (Full.ConstString x) = Type.String x
+constValue (Full.ConstBoolean b) = Type.Boolean b
+constValue Full.ConstNull = Type.Null
+constValue (Full.ConstEnum e) = Type.Enum e
+constValue (Full.ConstList l) = Type.List $ constValue <$> l
+constValue (Full.ConstObject o) =
+    Type.Object $ HashMap.fromList $ constObjectField <$> o
+  where
+    constObjectField Full.ObjectField{value = value', ..} =
+        (name, constValue $ Full.node value')
 
 -- | Rewrites the original syntax tree into an intermediate representation used
 -- for query execution.
-document :: Schema.Subs -> Document -> Maybe Core.Document
-document subs document' =
-    flip runReaderT subs
-        $ evalStateT (collectFragments >> operations operationDefinitions)
-        $ Replacement HashMap.empty fragmentTable
+document :: Coerce.VariableValue a
+    => forall m
+    . Type.Schema m
+    -> Maybe Full.Name
+    -> HashMap Full.Name a
+    -> Full.Document
+    -> Either QueryError (Document m)
+document schema operationName subs ast = do
+    let referencedTypes = Schema.types schema
+
+    (operations, fragmentTable) <- defragment ast
+    chosenOperation <- getOperation operationName operations
+    coercedValues <- coerceVariableValues referencedTypes chosenOperation subs
+
+    let replacement = Replacement
+            { fragments = HashMap.empty
+            , fragmentDefinitions = fragmentTable
+            , variableValues = coercedValues
+            , types = referencedTypes
+            }
+    case chosenOperation of
+        OperationDefinition Full.Query _ _ _ _ ->
+            pure $ Document referencedTypes (Schema.query schema)
+                $ operation chosenOperation replacement
+        OperationDefinition Full.Mutation _ _ _ _
+            | Just mutationType <- Schema.mutation schema ->
+                pure $ Document referencedTypes mutationType
+                    $ operation chosenOperation replacement
+        OperationDefinition Full.Subscription _ _ _ _
+            | Just subscriptionType <- Schema.subscription schema ->
+                pure $ Document referencedTypes subscriptionType
+                    $ operation chosenOperation replacement
+        _ -> Left UnsupportedRootOperation
+
+defragment
+    :: Full.Document
+    -> Either QueryError (NonEmpty OperationDefinition, FragmentDefinitions)
+defragment ast =
+    let (operations, fragmentTable) = foldr defragment' ([], HashMap.empty) ast
+        nonEmptyOperations = NonEmpty.nonEmpty operations
+        emptyDocument = Left EmptyDocument
+     in (, fragmentTable) <$> maybe emptyDocument Right nonEmptyOperations
   where
-    (fragmentTable, operationDefinitions) = foldr defragment mempty document'
-    defragment (ExecutableDefinition (Full.DefinitionOperation definition)) acc =
-        (definition :) <$> acc
-    defragment (ExecutableDefinition (Full.DefinitionFragment definition)) acc =
-        let (Full.FragmentDefinition name _ _ _) = definition
-         in first (HashMap.insert name definition) acc
-    defragment _ acc = acc
+    defragment' definition (operations, fragments')
+        | (Full.ExecutableDefinition executable) <- definition
+        , (Full.DefinitionOperation operation') <- executable =
+            (transform operation' : operations, fragments')
+        | (Full.ExecutableDefinition executable) <- definition
+        , (Full.DefinitionFragment fragment) <- executable
+        , (Full.FragmentDefinition name _ _ _ _) <- fragment =
+            (operations, HashMap.insert name fragment fragments')
+    defragment' _ acc = acc
+    transform = \case
+        Full.OperationDefinition type' name variables directives' selections _ ->
+            OperationDefinition type' name variables directives' selections
+        Full.SelectionSet selectionSet _ ->
+            OperationDefinition Full.Query Nothing mempty mempty selectionSet
 
 -- * Operation
 
-operations :: [Full.OperationDefinition] -> TransformT Core.Document
-operations operations' = do
-    coreOperations <- traverse operation operations'
-    lift . lift $ NonEmpty.nonEmpty coreOperations
-
-operation :: Full.OperationDefinition -> TransformT Core.Operation
-operation (Full.SelectionSet sels)
-    = operation $ Full.OperationDefinition Full.Query mempty mempty mempty sels
-operation (Full.OperationDefinition Full.Query name _vars _dirs sels)
-    = Core.Query name <$> appendSelection sels
-operation (Full.OperationDefinition Full.Mutation name _vars _dirs sels)
-    = Core.Mutation name <$> appendSelection sels
+operation :: OperationDefinition -> Replacement m -> Operation m
+operation operationDefinition replacement
+    = runIdentity
+    $ evalStateT (collectFragments >> transform operationDefinition) replacement
+  where
+    transform (OperationDefinition Full.Query name _ _ sels) =
+        Query name <$> appendSelection sels
+    transform (OperationDefinition Full.Mutation name _ _ sels) =
+        Mutation name <$> appendSelection sels
+    transform (OperationDefinition Full.Subscription name _ _ sels) =
+        Subscription name <$> appendSelection sels
 
 -- * Selection
 
-selection ::
-    Full.Selection ->
-    TransformT (Either (Seq Core.Selection) Core.Selection)
-selection (Full.Field alias name arguments' directives' selections) =
-    maybe (Left mempty) (Right . Core.SelectionField) <$> do
-        fieldArguments <- arguments arguments'
-        fieldSelections <- appendSelection selections
-        fieldDirectives <- Directive.selection <$> directives directives'
-        let field' = Core.Field alias name fieldArguments fieldSelections
-        pure $ field' <$ fieldDirectives
-selection (Full.FragmentSpread name directives') =
-    maybe (Left mempty) (Right . Core.SelectionFragment) <$> do
-        spreadDirectives <- Directive.selection <$> directives directives'
-        fragments' <- gets fragments
-        fragment <- maybe lookupDefinition liftJust (HashMap.lookup name fragments')
-        pure $ fragment <$ spreadDirectives
+selection
+    :: Full.Selection
+    ->  State (Replacement m) (Either (Seq (Selection m)) (Selection m))
+selection (Full.FieldSelection fieldSelection) =
+    maybe (Left mempty) (Right . SelectionField) <$> field fieldSelection
+selection (Full.FragmentSpreadSelection fragmentSelection)
+    = maybe (Left mempty) (Right . SelectionFragment)
+    <$> fragmentSpread fragmentSelection
+selection (Full.InlineFragmentSelection fragmentSelection) =
+    inlineFragment fragmentSelection
+
+field :: Full.Field ->  State (Replacement m) (Maybe (Field m))
+field (Full.Field alias name arguments' directives' selections _) = do
+    fieldArguments <- foldM go HashMap.empty arguments'
+    fieldSelections <- appendSelection selections
+    fieldDirectives <- Definition.selection <$> directives directives'
+    let field' = Field alias name fieldArguments fieldSelections
+    pure $ field' <$ fieldDirectives
   where
-    lookupDefinition = do
-        fragmentDefinitions' <- gets fragmentDefinitions
-        found <- lift . lift $ HashMap.lookup name fragmentDefinitions'
-        fragmentDefinition found
-selection (Full.InlineFragment type' directives' selections) = do
-    fragmentDirectives <- Directive.selection <$> directives directives'
+    go arguments (Full.Argument name' (Full.Node value' _) _) =
+        inputField arguments name' value'
+
+fragmentSpread
+    :: Full.FragmentSpread
+    -> State (Replacement m) (Maybe (Fragment m))
+fragmentSpread (Full.FragmentSpread name directives' _) = do
+    spreadDirectives <- Definition.selection <$> directives directives'
+    fragments' <- gets fragments
+
+    fragmentDefinitions' <- gets fragmentDefinitions
+    case HashMap.lookup name fragments' of
+        Just definition -> lift $ pure $ definition <$ spreadDirectives
+        Nothing
+            | Just definition <- HashMap.lookup name fragmentDefinitions' -> do
+                fragDef <- fragmentDefinition definition
+                case fragDef of
+                    Just fragment -> lift $ pure $ fragment <$ spreadDirectives
+                    _ -> lift $ pure  Nothing
+            | otherwise -> lift $ pure  Nothing
+
+inlineFragment
+    :: Full.InlineFragment
+    ->  State (Replacement m) (Either (Seq (Selection m)) (Selection m))
+inlineFragment (Full.InlineFragment type' directives' selections _) = do
+    fragmentDirectives <- Definition.selection <$> directives directives'
     case fragmentDirectives of
         Nothing -> pure $ Left mempty
         _ -> do
             fragmentSelectionSet <- appendSelection selections
-            pure $ maybe Left selectionFragment type' fragmentSelectionSet
+
+            case type' of
+                Nothing -> pure $ Left fragmentSelectionSet
+                Just typeName -> do
+                    types' <- gets types
+                    case Type.lookupTypeCondition typeName types' of
+                        Just typeCondition -> pure $
+                            selectionFragment typeCondition fragmentSelectionSet
+                        Nothing -> pure $ Left mempty
   where
     selectionFragment typeName = Right
-        . Core.SelectionFragment
-        . Core.Fragment typeName
+        . SelectionFragment
+        . Fragment typeName
 
-appendSelection ::
-    Traversable t =>
-    t Full.Selection ->
-    TransformT (Seq Core.Selection)
+appendSelection :: Traversable t
+    => t Full.Selection
+    ->  State (Replacement m) (Seq (Selection m))
 appendSelection = foldM go mempty
   where
     go acc sel = append acc <$> selection sel
     append acc (Left list) = list >< acc
     append acc (Right one) = one <| acc
 
-directives :: [Full.Directive] -> TransformT [Core.Directive]
+directives :: [Full.Directive] ->  State (Replacement m) [Definition.Directive]
 directives = traverse directive
   where
-    directive (Full.Directive directiveName directiveArguments) =
-        Core.Directive directiveName <$> arguments directiveArguments
+    directive (Full.Directive directiveName directiveArguments _)
+        = Definition.Directive directiveName . Type.Arguments
+        <$> foldM go HashMap.empty directiveArguments
+    go arguments (Full.Argument name (Full.Node value' _) _) = do
+        substitutedValue <- value value'
+        return $ HashMap.insert name substitutedValue arguments
 
 -- * Fragment replacement
 
 -- | Extract fragment definitions into a single 'HashMap'.
-collectFragments :: TransformT ()
+collectFragments ::  State (Replacement m) ()
 collectFragments = do
     fragDefs <- gets fragmentDefinitions
     let nextValue = head $ HashMap.elems fragDefs
@@ -127,41 +349,68 @@ collectFragments = do
         _ <- fragmentDefinition nextValue
         collectFragments
 
-fragmentDefinition ::
-    Full.FragmentDefinition ->
-    TransformT Core.Fragment
-fragmentDefinition (Full.FragmentDefinition name type' _ selections) = do
+fragmentDefinition
+    :: Full.FragmentDefinition
+    ->  State (Replacement m) (Maybe (Fragment m))
+fragmentDefinition (Full.FragmentDefinition name type' _ selections _) = do
     modify deleteFragmentDefinition
     fragmentSelection <- appendSelection selections
-    let newValue = Core.Fragment type' fragmentSelection
-    modify $ insertFragment newValue
-    liftJust newValue
+    types' <- gets types
+
+    case Type.lookupTypeCondition type' types' of
+        Just compositeType -> do
+            let newValue = Fragment compositeType fragmentSelection
+            modify $ insertFragment newValue
+            lift $ pure $ Just newValue
+        _ -> lift $ pure Nothing
   where
-    deleteFragmentDefinition (Replacement fragments' fragmentDefinitions') =
-        Replacement fragments' $ HashMap.delete name fragmentDefinitions'
-    insertFragment newValue (Replacement fragments' fragmentDefinitions') =
-        let newFragments = HashMap.insert name newValue fragments'
-         in Replacement newFragments fragmentDefinitions'
+    deleteFragmentDefinition replacement@Replacement{..} =
+        let newDefinitions = HashMap.delete name fragmentDefinitions
+         in replacement{ fragmentDefinitions = newDefinitions }
+    insertFragment newValue replacement@Replacement{..} =
+        let newFragments = HashMap.insert name newValue fragments
+         in replacement{ fragments = newFragments }
 
-arguments :: [Full.Argument] -> TransformT Core.Arguments
-arguments = fmap Core.Arguments . foldM go HashMap.empty
+value :: forall m. Full.Value -> State (Replacement m) Type.Value
+value (Full.Variable name) =
+    gets (fromMaybe Type.Null . HashMap.lookup name . variableValues)
+value (Full.Int int) = pure $ Type.Int int
+value (Full.Float float) = pure $ Type.Float float
+value (Full.String string) = pure $ Type.String string
+value (Full.Boolean boolean) = pure $ Type.Boolean boolean
+value Full.Null = pure Type.Null
+value (Full.Enum enum) = pure $ Type.Enum enum
+value (Full.List list) = Type.List <$> traverse value list
+value (Full.Object object) =
+    Type.Object . HashMap.fromList <$> traverse objectField object
   where
-    go arguments' (Full.Argument name value') = do
-        substitutedValue <- value value'
-        return $ HashMap.insert name substitutedValue arguments'
+    objectField Full.ObjectField{value = value', ..} =
+        (name,) <$> value (Full.node value')
 
-value :: Full.Value -> TransformT Core.Value
-value (Full.Variable name) = lift (asks $ HashMap.lookup name) >>= lift . lift
-value (Full.Int i) = pure $ Core.Int i
-value (Full.Float f) = pure $ Core.Float f
-value (Full.String x) = pure $ Core.String x
-value (Full.Boolean b) = pure $ Core.Boolean b
-value Full.Null = pure   Core.Null
-value (Full.Enum e) = pure $ Core.Enum e
-value (Full.List l) =
-    Core.List <$> traverse value l
-value (Full.Object o) =
-    Core.Object . HashMap.fromList <$> traverse objectField o
+input :: forall m. Full.Value -> State (Replacement m) (Maybe Input)
+input (Full.Variable name) =
+    gets (fmap Variable . HashMap.lookup name . variableValues)
+input (Full.Int int) = pure $ pure $ Int int
+input (Full.Float float) = pure $ pure $ Float float
+input (Full.String string) = pure $ pure $ String string
+input (Full.Boolean boolean) = pure $ pure $ Boolean boolean
+input Full.Null = pure $ pure Null
+input (Full.Enum enum) = pure $ pure $ Enum enum
+input (Full.List list) = pure . List <$> traverse value list
+input (Full.Object object) = do
+    objectFields <- foldM objectField HashMap.empty object
+    pure $ pure $ Object objectFields
+  where
+    objectField resultMap Full.ObjectField{value = value', ..} =
+        inputField resultMap name $ Full.node value'
 
-objectField :: Full.ObjectField -> TransformT (Core.Name, Core.Value)
-objectField (Full.ObjectField name value') = (name,) <$> value value'
+inputField :: forall m
+    . HashMap Full.Name Input
+    -> Full.Name
+    -> Full.Value
+    -> State (Replacement m) (HashMap Full.Name Input)
+inputField resultMap name value' = do
+    objectFieldValue <-  input value'
+    case objectFieldValue of
+        Just fieldValue -> pure $ HashMap.insert name fieldValue resultMap
+        Nothing -> pure resultMap

src/Language/GraphQL/Schema.hs

@@ -1,138 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-
--- | This module provides a representation of a @GraphQL@ Schema in addition to
--- functions for defining and manipulating schemas.
-module Language.GraphQL.Schema
-    ( Resolver(..)
-    , Subs
-    , object
-    , resolve
-    , resolversToMap
-    , scalar
-    , wrappedObject
-    , wrappedScalar
-    -- * AST Reexports
-    , Field
-    , Value(..)
-    ) where
-
-import Control.Monad.Trans.Class (lift)
-import Control.Monad.Trans.Except (runExceptT)
-import Control.Monad.Trans.Reader (runReaderT)
-import Data.Foldable (fold, toList)
-import Data.Maybe (fromMaybe)
-import qualified Data.Aeson as Aeson
-import Data.HashMap.Strict (HashMap)
-import qualified Data.HashMap.Strict as HashMap
-import Data.Sequence (Seq)
-import Data.Text (Text)
-import qualified Data.Text as T
-import Language.GraphQL.AST.Core
-import Language.GraphQL.Error
-import Language.GraphQL.Trans
-import qualified Language.GraphQL.Type as Type
-
--- | Resolves a 'Field' into an @Aeson.@'Data.Aeson.Types.Object' with error
---   information (if an error has occurred). @m@ is an arbitrary monad, usually
---   'IO'.
-data Resolver m = Resolver
-    Text -- ^ Name
-    (Field -> CollectErrsT m Aeson.Object) -- ^ Resolver
-
--- | Converts resolvers to a map.
-resolversToMap
-    :: (Foldable f, Functor f)
-    => f (Resolver m)
-    -> HashMap Text (Field -> CollectErrsT m Aeson.Object)
-resolversToMap = HashMap.fromList . toList . fmap toKV
-  where
-    toKV (Resolver name f) = (name, f)
-
--- | Contains variables for the query. The key of the map is a variable name,
---   and the value is the variable value.
-type Subs = HashMap Name Value
-
--- | Create a new 'Resolver' with the given 'Name' from the given 'Resolver's.
-object :: Monad m => Name -> ActionT m [Resolver m] -> Resolver m
-object name f = Resolver name $ resolveFieldValue f resolveRight
-  where
-    resolveRight fld@(Field _ _ _ flds) resolver
-        = withField (resolve (resolversToMap resolver) flds) fld
-
--- | Like 'object' but can be null or a list of objects.
-wrappedObject ::
-    Monad m =>
-    Name ->
-    ActionT m (Type.Wrapping [Resolver m]) ->
-    Resolver m
-wrappedObject name f = Resolver name $ resolveFieldValue f resolveRight
-  where
-    resolveRight fld@(Field _ _ _ sels) resolver
-        = withField (traverse (resolveMap sels) resolver) fld
-    resolveMap = flip (resolve . resolversToMap)
-
--- | A scalar represents a primitive value, like a string or an integer.
-scalar :: (Monad m, Aeson.ToJSON a) => Name -> ActionT m a -> Resolver m
-scalar name f = Resolver name $ resolveFieldValue f resolveRight
-  where
-    resolveRight fld result = withField (return result) fld
-
--- | Like 'scalar' but can be null or a list of scalars.
-wrappedScalar ::
-    (Monad m, Aeson.ToJSON a) =>
-    Name ->
-    ActionT m (Type.Wrapping a) ->
-    Resolver m
-wrappedScalar name f = Resolver name $ resolveFieldValue f resolveRight
-  where
-    resolveRight fld (Type.Named result) = withField (return result) fld
-    resolveRight fld Type.Null
-        = return $ HashMap.singleton (aliasOrName fld) Aeson.Null
-    resolveRight fld (Type.List result) = withField (return result) fld
-
-resolveFieldValue ::
-    Monad m =>
-    ActionT m a ->
-    (Field -> a -> CollectErrsT m Aeson.Object) ->
-    Field ->
-    CollectErrsT m (HashMap Text Aeson.Value)
-resolveFieldValue f resolveRight fld@(Field _ _ args _) = do
-    result <- lift $ reader . runExceptT . runActionT $ f
-    either resolveLeft (resolveRight fld) result
-      where
-        reader = flip runReaderT $ Context {arguments=args}
-        resolveLeft err = do
-            _ <- addErrMsg err
-            return $ HashMap.singleton (aliasOrName fld) Aeson.Null
-
--- | Helper function to facilitate error handling and result emitting.
-withField :: (Monad m, Aeson.ToJSON a)
-    => CollectErrsT m a -> Field -> CollectErrsT m (HashMap Text Aeson.Value)
-withField v fld
-    = HashMap.singleton (aliasOrName fld) . Aeson.toJSON <$> runAppendErrs v
-
--- | Takes a list of 'Resolver's and a list of 'Field's and applies each
---   'Resolver' to each 'Field'. Resolves into a value containing the
---   resolved 'Field', or a null value and error information.
-resolve :: Monad m
-    => HashMap Text (Field -> CollectErrsT m Aeson.Object)
-    -> Seq Selection
-    -> CollectErrsT m Aeson.Value
-resolve resolvers = fmap (Aeson.toJSON . fold) . traverse tryResolvers
-  where
-    resolveTypeName f = do
-        value <- f $ Field Nothing "__typename" mempty mempty
-        return $ HashMap.lookupDefault "" "__typename" value
-    tryResolvers (SelectionField fld@(Field _ name _ _))
-        = fromMaybe (errmsg fld) $ HashMap.lookup name resolvers <*> Just fld
-    tryResolvers (SelectionFragment (Fragment typeCondition selections')) = do
-        that <- traverse resolveTypeName $ HashMap.lookup "__typename" resolvers
-        if maybe True (Aeson.String typeCondition ==) that
-            then fmap fold . traverse tryResolvers $ selections'
-            else return mempty
-    errmsg fld@(Field _ name _ _) = do
-        addErrMsg $ T.unwords ["field", name, "not resolved."]
-        return $ HashMap.singleton (aliasOrName fld) Aeson.Null
-
-aliasOrName :: Field -> Text
-aliasOrName (Field alias name _ _) = fromMaybe name alias

src/Language/GraphQL/Trans.hs

@@ -1,64 +0,0 @@
--- | Monad transformer stack used by the @GraphQL@ resolvers.
-module Language.GraphQL.Trans
-    ( ActionT(..)
-    , Context(..)
-    , argument
-    ) where
-
-import Control.Applicative (Alternative(..))
-import Control.Monad (MonadPlus(..))
-import Control.Monad.IO.Class (MonadIO(..))
-import Control.Monad.Trans.Class (MonadTrans(..))
-import Control.Monad.Trans.Except (ExceptT)
-import Control.Monad.Trans.Reader (ReaderT, asks)
-import qualified Data.HashMap.Strict as HashMap
-import Data.Maybe (fromMaybe)
-import Data.Text (Text)
-import Language.GraphQL.AST.Core
-import Prelude hiding (lookup)
-
--- | Resolution context holds resolver arguments.
-newtype Context = Context
-    { arguments :: Arguments
-    }
-
--- | Monad transformer stack used by the resolvers to provide error handling
---   and resolution context (resolver arguments).
-newtype ActionT m a = ActionT
-    { runActionT :: ExceptT Text (ReaderT Context m) a
-    }
-
-instance Functor m => Functor (ActionT m) where
-    fmap f = ActionT . fmap f . runActionT
-
-instance Monad m => Applicative (ActionT m) where
-    pure = ActionT . pure
-    (ActionT f) <*> (ActionT x) = ActionT $ f <*> x
-
-instance Monad m => Monad (ActionT m) where
-    return = pure
-    (ActionT action) >>= f = ActionT $ action >>= runActionT . f
-
-instance MonadTrans ActionT where
-    lift = ActionT . lift . lift
-
-instance MonadIO m => MonadIO (ActionT m) where
-    liftIO = lift . liftIO
-
-instance Monad m => Alternative (ActionT m) where
-    empty = ActionT empty
-    (ActionT x) <|> (ActionT y) = ActionT $ x <|> y
-
-instance Monad m => MonadPlus (ActionT m) where
-    mzero = empty
-    mplus = (<|>)
-
--- | Retrieves an argument by its name. If the argument with this name couldn't
---   be found, returns 'Value.Null' (i.e. the argument is assumed to
---   be optional then).
-argument :: Monad m => Name -> ActionT m Value
-argument argumentName = do
-    argumentValue <- ActionT $ lift $ asks $ lookup . arguments
-    pure $ fromMaybe Null argumentValue
-  where
-    lookup (Arguments argumentMap) = HashMap.lookup argumentName argumentMap

src/Language/GraphQL/Type.hs

@@ -1,55 +1,26 @@
--- | Definitions for @GraphQL@ input types.
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+-- | Reexports non-conflicting type system and schema definitions.
 module Language.GraphQL.Type
-    ( Wrapping(..)
+    ( In.InputField(..)
+    , In.InputObjectType(..)
+    , Out.Context(..)
+    , Out.Field(..)
+    , Out.InterfaceType(..)
+    , Out.ObjectType(..)
+    , Out.Resolve
+    , Out.Resolver(..)
+    , Out.SourceEventStream
+    , Out.Subscribe
+    , Out.UnionType(..)
+    , Out.argument
+    , module Language.GraphQL.Type.Definition
+    , module Language.GraphQL.Type.Schema
     ) where
 
-import Data.Aeson as Aeson (ToJSON, toJSON)
-import qualified Data.Aeson as Aeson
-
--- | GraphQL distinguishes between "wrapping" and "named" types. Each wrapping
---   type can wrap other wrapping or named types. Wrapping types are lists and
---   Non-Null types (named types are nullable by default).
---
---   This 'Wrapping' type doesn\'t reflect this distinction exactly but it is
---   used in the resolvers to take into account that the returned value can be
---   nullable or an (arbitrary nested) list.
-data Wrapping a
-    = List [Wrapping a] -- ^ Arbitrary nested list
-    | Named a -- ^ Named type without further wrapping
-    | Null -- ^ Null
-    deriving (Eq, Show)
-
-instance Functor Wrapping where
-    fmap f (List list) = List $ fmap (fmap f) list
-    fmap f (Named named) = Named $ f named
-    fmap _ Null = Null
-
-instance Foldable Wrapping where
-    foldr f acc (List list) = foldr (flip $ foldr f) acc list
-    foldr f acc (Named named) = f named acc
-    foldr _ acc Null = acc
-
-instance Traversable Wrapping where
-    traverse f (List list) = List <$> traverse (traverse f) list
-    traverse f (Named named) = Named <$> f named
-    traverse _ Null = pure Null
-
-instance Applicative Wrapping where
-    pure = Named
-    Null <*> _ = Null
-    _ <*> Null = Null
-    (Named f) <*> (Named x) = Named $ f x
-    (List fs) <*> (List xs) = List $ (<*>) <$> fs <*> xs
-    (Named f) <*> list = f <$> list
-    (List fs) <*> named = List $ (<*> named) <$> fs
-
-instance Monad Wrapping where
-    return = pure
-    Null >>= _ = Null
-    (Named x) >>= f = f x
-    (List xs) >>= f = List $ fmap (>>= f) xs
-
-instance ToJSON a => ToJSON (Wrapping a) where
-    toJSON (List list) = toJSON list
-    toJSON (Named named) = toJSON named
-    toJSON Null = Aeson.Null
+import Language.GraphQL.Type.Definition
+import Language.GraphQL.Type.Schema (Schema, schema)
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out

src/Language/GraphQL/Type/Definition.hs

@@ -0,0 +1,175 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+-- | Types that can be used as both input and output types.
+module Language.GraphQL.Type.Definition
+    ( Arguments(..)
+    , Directive(..)
+    , EnumType(..)
+    , EnumValue(..)
+    , ScalarType(..)
+    , Subs
+    , Value(..)
+    , boolean
+    , float
+    , id
+    , int
+    , selection
+    , string
+    ) where
+
+import Data.Int (Int32)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.String (IsString(..))
+import Data.Text (Text)
+import Language.GraphQL.AST (Name)
+import Prelude hiding (id)
+
+-- | Represents accordingly typed GraphQL values.
+data Value
+    = Int Int32
+    | Float Double -- ^ GraphQL Float is double precision.
+    | String Text
+    | Boolean Bool
+    | Null
+    | Enum Name
+    | List [Value] -- ^ Arbitrary nested list.
+    | Object (HashMap Name Value)
+    deriving (Eq, Show)
+
+instance IsString Value where
+    fromString = String . fromString
+
+-- | Contains variables for the query. The key of the map is a variable name,
+-- and the value is the variable value.
+type Subs = HashMap Name Value
+
+-- | Argument list.
+newtype Arguments = Arguments (HashMap Name Value)
+    deriving (Eq, Show)
+
+instance Semigroup Arguments where
+    (Arguments x) <> (Arguments y) = Arguments $ x <> y
+
+instance Monoid Arguments where
+    mempty = Arguments mempty
+
+-- | Scalar type definition.
+--
+-- The leaf values of any request and input values to arguments are Scalars (or
+-- Enums) .
+data ScalarType = ScalarType Name (Maybe Text)
+
+instance Eq ScalarType where
+    (ScalarType this _) == (ScalarType that _) = this == that
+
+-- | Enum type definition.
+--
+-- Some leaf values of requests and input values are Enums. GraphQL serializes
+-- Enum values as strings, however internally Enums can be represented by any
+-- kind of type, often integers.
+data EnumType = EnumType Name (Maybe Text) (HashMap Name EnumValue)
+
+instance Eq EnumType where
+    (EnumType this _ _) == (EnumType that _ _) = this == that
+
+-- | Enum value is a single member of an 'EnumType'.
+newtype EnumValue = EnumValue (Maybe Text)
+
+-- | The @String@ scalar type represents textual data, represented as UTF-8
+-- character sequences. The String type is most often used by GraphQL to
+-- represent free-form human-readable text.
+string :: ScalarType
+string = ScalarType "String" (Just description)
+  where
+    description =
+        "The `String` scalar type represents textual data, represented as \
+        \UTF-8 character sequences. The String type is most often used by \
+        \GraphQL to represent free-form human-readable text."
+
+-- | The @Boolean@ scalar type represents @true@ or @false@.
+boolean :: ScalarType
+boolean = ScalarType "Boolean" (Just description)
+  where
+    description = "The `Boolean` scalar type represents `true` or `false`."
+
+-- | The @Int@ scalar type represents non-fractional signed whole numeric
+-- values. Int can represent values between \(-2^{31}\) and \(2^{31 - 1}\).
+int :: ScalarType
+int = ScalarType "Int" (Just description)
+  where
+    description =
+        "The `Int` scalar type represents non-fractional signed whole numeric \
+        \values. Int can represent values between -(2^31) and 2^31 - 1."
+
+-- | The @Float@ scalar type represents signed double-precision fractional
+-- values as specified by
+-- [IEEE 754](https://en.wikipedia.org/wiki/IEEE_floating_point).
+float :: ScalarType
+float = ScalarType "Float" (Just description)
+  where
+    description =
+        "The `Float` scalar type represents signed double-precision fractional \
+        \values as specified by \
+        \[IEEE 754](https://en.wikipedia.org/wiki/IEEE_floating_point)."
+
+-- | The @ID@ scalar type represents a unique identifier, often used to refetch
+-- an object or as key for a cache. The ID type appears in a JSON response as a
+-- String; however, it is not intended to be human-readable. When expected as an
+-- input type, any string (such as @"4"@) or integer (such as @4@) input value
+-- will be accepted as an ID.
+id :: ScalarType
+id = ScalarType "ID" (Just description)
+  where
+    description =
+        "The `ID` scalar type represents a unique identifier, often used to \
+        \refetch an object or as key for a cache. The ID type appears in a \
+        \JSON response as a String; however, it is not intended to be \
+        \human-readable. When expected as an input type, any string (such as \
+        \`\"4\"`) or integer (such as `4`) input value will be accepted as an ID."
+
+-- | Directive.
+data Directive = Directive Name Arguments
+    deriving (Eq, Show)
+
+-- | Directive processing status.
+data Status
+    = Skip -- ^ Skip the selection and stop directive processing
+    | Include Directive -- ^ The directive was processed, try other handlers
+    | Continue Directive -- ^ Directive handler mismatch, try other handlers
+
+-- | Takes a list of directives, handles supported directives and excludes them
+--   from the result. If the selection should be skipped, returns 'Nothing'.
+selection :: [Directive] -> Maybe [Directive]
+selection = foldr go (Just [])
+  where
+    go directive' directives' =
+        case (skip . include) (Continue directive') of
+            (Include _) -> directives'
+            Skip -> Nothing
+            (Continue x) -> (x :) <$> directives'
+
+handle :: (Directive -> Status) -> Status -> Status
+handle _ Skip = Skip
+handle handler (Continue directive) = handler directive
+handle handler (Include directive) = handler directive
+
+-- * Directive implementations
+
+skip :: Status -> Status
+skip = handle skip'
+  where
+    skip' directive'@(Directive "skip" (Arguments arguments)) =
+        case HashMap.lookup "if" arguments of
+            (Just (Boolean True)) -> Skip
+            _ -> Include directive'
+    skip' directive' = Continue directive'
+
+include :: Status -> Status
+include = handle include'
+  where
+    include' directive'@(Directive "include" (Arguments arguments)) =
+        case HashMap.lookup "if" arguments of
+            (Just (Boolean True)) -> Include directive'
+            _ -> Skip
+    include' directive' = Continue directive'

src/Language/GraphQL/Type/Directive.hs

@@ -1,50 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-
-module Language.GraphQL.Type.Directive
-    ( selection
-    ) where
-
-import qualified Data.HashMap.Strict as HashMap
-import Language.GraphQL.AST.Core
-
--- | Directive processing status.
-data Status
-    = Skip -- ^ Skip the selection and stop directive processing
-    | Include Directive -- ^ The directive was processed, try other handlers
-    | Continue Directive -- ^ Directive handler mismatch, try other handlers
-
--- | Takes a list of directives, handles supported directives and excludes them
---   from the result. If the selection should be skipped, returns 'Nothing'.
-selection :: [Directive] -> Maybe [Directive]
-selection = foldr go (Just [])
-  where
-    go directive' directives' =
-        case (skip . include) (Continue directive') of
-            (Include _) -> directives'
-            Skip -> Nothing
-            (Continue x) -> (x :) <$> directives'
-
-handle :: (Directive -> Status) -> Status -> Status
-handle _ Skip = Skip
-handle handler (Continue directive) = handler directive
-handle handler (Include directive) = handler directive
-
--- * Directive implementations
-
-skip :: Status -> Status
-skip = handle skip'
-  where
-    skip' directive'@(Directive "skip" (Arguments arguments)) =
-        case HashMap.lookup "if" arguments of
-            (Just (Boolean True)) -> Skip
-            _ -> Include directive'
-    skip' directive' = Continue directive'
-
-include :: Status -> Status
-include = handle include'
-  where
-    include' directive'@(Directive "include" (Arguments arguments)) =
-        case HashMap.lookup "if" arguments of
-            (Just (Boolean True)) -> Include directive'
-            _ -> Skip
-    include' directive' = Continue directive'

src/Language/GraphQL/Type/In.hs

@@ -0,0 +1,109 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE ViewPatterns #-}
+
+-- | Input types and values.
+--
+-- This module is intended to be imported qualified, to avoid name clashes
+-- with 'Language.GraphQL.Type.Out'.
+module Language.GraphQL.Type.In
+    ( Argument(..)
+    , Arguments
+    , InputField(..)
+    , InputObjectType(..)
+    , Type(..)
+    , isNonNullType
+    , pattern EnumBaseType
+    , pattern ListBaseType
+    , pattern InputObjectBaseType
+    , pattern ScalarBaseType
+    ) where
+
+import Data.HashMap.Strict (HashMap)
+import Data.Text (Text)
+import Language.GraphQL.AST.Document (Name)
+import qualified Language.GraphQL.Type.Definition as Definition
+
+-- | Single field of an 'InputObjectType'.
+data InputField = InputField (Maybe Text) Type (Maybe Definition.Value)
+
+-- | Input object type definition.
+--
+-- An input object defines a structured collection of fields which may be
+-- supplied to a field argument.
+data InputObjectType = InputObjectType
+    Name (Maybe Text) (HashMap Name InputField)
+
+instance Eq InputObjectType where
+    (InputObjectType this _ _) == (InputObjectType that _ _) = this == that
+
+-- | These types may be used as input types for arguments and directives.
+--
+-- GraphQL distinguishes between "wrapping" and "named" types. Each wrapping
+-- type can wrap other wrapping or named types. Wrapping types are lists and
+-- Non-Null types (named types are nullable by default).
+data Type
+    = NamedScalarType Definition.ScalarType
+    | NamedEnumType Definition.EnumType
+    | NamedInputObjectType InputObjectType
+    | ListType Type
+    | NonNullScalarType Definition.ScalarType
+    | NonNullEnumType Definition.EnumType
+    | NonNullInputObjectType InputObjectType
+    | NonNullListType Type
+    deriving Eq
+
+-- | Field argument definition.
+data Argument = Argument (Maybe Text) Type (Maybe Definition.Value)
+
+-- | Field argument definitions.
+type Arguments = HashMap Name Argument
+
+-- | Matches either 'NamedScalarType' or 'NonNullScalarType'.
+pattern ScalarBaseType :: Definition.ScalarType -> Type
+pattern ScalarBaseType scalarType <- (isScalarType -> Just scalarType)
+
+-- | Matches either 'NamedEnumType' or 'NonNullEnumType'.
+pattern EnumBaseType :: Definition.EnumType -> Type
+pattern EnumBaseType enumType <- (isEnumType -> Just enumType)
+
+-- | Matches either 'NamedInputObjectType' or 'NonNullInputObjectType'.
+pattern InputObjectBaseType :: InputObjectType -> Type
+pattern InputObjectBaseType objectType <- (isInputObjectType -> Just objectType)
+
+-- | Matches either 'ListType' or 'NonNullListType'.
+pattern ListBaseType :: Type -> Type
+pattern ListBaseType listType <- (isListType -> Just listType)
+
+{-# COMPLETE EnumBaseType, ListBaseType, InputObjectBaseType, ScalarBaseType #-}
+
+isScalarType :: Type -> Maybe Definition.ScalarType
+isScalarType (NamedScalarType inputType) = Just inputType
+isScalarType (NonNullScalarType inputType) = Just inputType
+isScalarType _ = Nothing
+
+isInputObjectType :: Type -> Maybe InputObjectType
+isInputObjectType (NamedInputObjectType inputType) = Just inputType
+isInputObjectType (NonNullInputObjectType inputType) = Just inputType
+isInputObjectType _ = Nothing
+
+isEnumType :: Type -> Maybe Definition.EnumType
+isEnumType (NamedEnumType inputType) = Just inputType
+isEnumType (NonNullEnumType inputType) = Just inputType
+isEnumType _ = Nothing
+
+isListType :: Type -> Maybe Type
+isListType (ListType inputType) = Just inputType
+isListType (NonNullListType inputType) = Just inputType
+isListType _ = Nothing
+
+-- | Checks whether the given input type is a non-null type.
+isNonNullType :: Type -> Bool
+isNonNullType (NonNullScalarType _) = True
+isNonNullType (NonNullEnumType _) = True
+isNonNullType (NonNullInputObjectType _) = True
+isNonNullType (NonNullListType _) = True
+isNonNullType _ = False

src/Language/GraphQL/Type/Internal.hs

@@ -0,0 +1,176 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE LambdaCase #-}
+
+module Language.GraphQL.Type.Internal
+    ( AbstractType(..)
+    , CompositeType(..)
+    , Directive(..)
+    , Directives
+    , Schema(..)
+    , Type(..)
+    , directives
+    , doesFragmentTypeApply
+    , instanceOf
+    , lookupInputType
+    , lookupTypeCondition
+    , lookupTypeField
+    , mutation
+    , subscription
+    , query
+    , types
+    ) where
+
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Text (Text)
+import qualified Language.GraphQL.AST as Full
+import Language.GraphQL.AST.DirectiveLocation (DirectiveLocation)
+import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+
+-- | These are all of the possible kinds of types.
+data Type m
+    = ScalarType Definition.ScalarType
+    | EnumType Definition.EnumType
+    | ObjectType (Out.ObjectType m)
+    | InputObjectType In.InputObjectType
+    | InterfaceType (Out.InterfaceType m)
+    | UnionType (Out.UnionType m)
+    deriving Eq
+
+-- | Directive definition.
+data Directive = Directive (Maybe Text) [DirectiveLocation] In.Arguments
+
+-- | Directive definitions.
+type Directives = HashMap Full.Name Directive
+
+-- | A Schema is created by supplying the root types of each type of operation,
+--   query and mutation (optional). A schema definition is then supplied to the
+--   validator and executor.
+--
+--   __Note:__ When the schema is constructed, by default only the types that
+--   are reachable by traversing the root types are included, other types must
+--   be explicitly referenced.
+data Schema m = Schema
+    (Out.ObjectType m)
+    (Maybe (Out.ObjectType m))
+    (Maybe (Out.ObjectType m))
+    Directives
+    (HashMap Full.Name (Type m))
+
+-- | Schema query type.
+query :: forall m. Schema m -> Out.ObjectType m
+query (Schema query' _ _ _ _) = query'
+
+-- | Schema mutation type.
+mutation :: forall m. Schema m -> Maybe (Out.ObjectType m)
+mutation (Schema _ mutation' _ _ _) = mutation'
+
+-- | Schema subscription type.
+subscription :: forall m. Schema m -> Maybe (Out.ObjectType m)
+subscription (Schema _ _ subscription' _ _) = subscription'
+
+-- | Schema directive definitions.
+directives :: forall m. Schema m -> Directives
+directives (Schema _ _ _ directives' _) = directives'
+
+-- | Types referenced by the schema.
+types :: forall m. Schema m -> HashMap Full.Name (Type m)
+types (Schema _ _ _ _ types') = types'
+
+-- | These types may describe the parent context of a selection set.
+data CompositeType m
+    = CompositeUnionType (Out.UnionType m)
+    | CompositeObjectType (Out.ObjectType m)
+    | CompositeInterfaceType (Out.InterfaceType m)
+    deriving Eq
+
+-- | These types may describe the parent context of a selection set.
+data AbstractType m
+    = AbstractUnionType (Out.UnionType m)
+    | AbstractInterfaceType (Out.InterfaceType m)
+    deriving Eq
+
+doesFragmentTypeApply :: forall m
+    . CompositeType m
+    -> Out.ObjectType m
+    -> Bool
+doesFragmentTypeApply (CompositeObjectType fragmentType) objectType =
+    fragmentType == objectType
+doesFragmentTypeApply (CompositeInterfaceType fragmentType) objectType =
+    instanceOf objectType $ AbstractInterfaceType fragmentType
+doesFragmentTypeApply (CompositeUnionType fragmentType) objectType =
+    instanceOf objectType $ AbstractUnionType fragmentType
+
+instanceOf :: forall m. Out.ObjectType m -> AbstractType m -> Bool
+instanceOf objectType (AbstractInterfaceType interfaceType) =
+    let Out.ObjectType _ _ interfaces _ = objectType
+     in foldr go False interfaces
+  where
+    go objectInterfaceType@(Out.InterfaceType _ _ interfaces _) acc =
+        acc || foldr go (interfaceType == objectInterfaceType) interfaces
+instanceOf objectType (AbstractUnionType unionType) =
+    let Out.UnionType _ _ members = unionType
+     in foldr go False members
+  where
+    go unionMemberType acc = acc || objectType == unionMemberType
+
+lookupTypeCondition :: forall m
+    . Full.Name
+    -> HashMap Full.Name (Type m)
+    -> Maybe (CompositeType m)
+lookupTypeCondition type' types' =
+    case HashMap.lookup type' types' of
+        Just (ObjectType objectType) ->
+            Just $ CompositeObjectType objectType
+        Just (UnionType unionType) -> Just $ CompositeUnionType unionType
+        Just (InterfaceType interfaceType) ->
+            Just $ CompositeInterfaceType interfaceType
+        _ -> Nothing
+
+lookupInputType :: Full.Type -> HashMap Full.Name (Type m) -> Maybe In.Type
+lookupInputType (Full.TypeNamed name) types' =
+    case HashMap.lookup name types' of
+        Just (ScalarType scalarType) ->
+            Just $ In.NamedScalarType scalarType
+        Just (EnumType enumType) ->
+            Just $ In.NamedEnumType enumType
+        Just (InputObjectType objectType) ->
+            Just $ In.NamedInputObjectType objectType
+        _ -> Nothing
+lookupInputType (Full.TypeList list) types'
+    = In.ListType
+    <$> lookupInputType list types'
+lookupInputType (Full.TypeNonNull (Full.NonNullTypeNamed nonNull)) types' =
+    case HashMap.lookup nonNull types' of
+        Just (ScalarType scalarType) ->
+            Just $ In.NonNullScalarType scalarType
+        Just (EnumType enumType) ->
+            Just $ In.NonNullEnumType enumType
+        Just (InputObjectType objectType) ->
+            Just $ In.NonNullInputObjectType objectType
+        _ -> Nothing
+lookupInputType (Full.TypeNonNull (Full.NonNullTypeList nonNull)) types'
+    = In.NonNullListType
+    <$> lookupInputType nonNull types'
+
+lookupTypeField :: forall a. Full.Name -> Out.Type a -> Maybe (Out.Field a)
+lookupTypeField fieldName = \case
+    Out.ObjectBaseType objectType ->
+        objectChild objectType
+    Out.InterfaceBaseType interfaceType ->
+        interfaceChild interfaceType
+    Out.ListBaseType listType -> lookupTypeField fieldName listType
+    _ -> Nothing
+  where
+    objectChild (Out.ObjectType _ _ _ resolvers) =
+        resolverType <$> HashMap.lookup fieldName resolvers
+    interfaceChild (Out.InterfaceType _ _ _ fields) =
+        HashMap.lookup fieldName fields
+    resolverType (Out.ValueResolver objectField _) = objectField
+    resolverType (Out.EventStreamResolver objectField _ _) = objectField

src/Language/GraphQL/Type/Out.hs

@@ -0,0 +1,212 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE ViewPatterns #-}
+
+-- | Output types and values, monad transformer stack used by the @GraphQL@
+-- resolvers.
+--
+-- This module is intended to be imported qualified, to avoid name clashes
+-- with 'Language.GraphQL.Type.In'.
+module Language.GraphQL.Type.Out
+    ( Context(..)
+    , Field(..)
+    , InterfaceType(..)
+    , ObjectType(..)
+    , Resolve
+    , Subscribe
+    , Resolver(..)
+    , SourceEventStream
+    , Type(..)
+    , UnionType(..)
+    , argument
+    , isNonNullType
+    , pattern EnumBaseType
+    , pattern InterfaceBaseType
+    , pattern ListBaseType
+    , pattern ObjectBaseType
+    , pattern ScalarBaseType
+    , pattern UnionBaseType
+    ) where
+
+import Conduit
+import Control.Monad.Trans.Reader (ReaderT, asks)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Maybe (fromMaybe)
+import Data.Text (Text)
+import Language.GraphQL.AST (Name)
+import Language.GraphQL.Type.Definition
+import qualified Language.GraphQL.Type.In as In
+
+-- | Object type definition.
+--
+-- Almost all of the GraphQL types you define will be object types. Object
+-- types have a name, but most importantly describe their fields.
+data ObjectType m = ObjectType
+    Name (Maybe Text) [InterfaceType m] (HashMap Name (Resolver m))
+
+instance forall a. Eq (ObjectType a) where
+    (ObjectType this _ _ _) == (ObjectType that _ _ _) = this == that
+
+-- | Interface Type Definition.
+--
+-- When a field can return one of a heterogeneous set of types, a Interface type
+-- is used to describe what types are possible, and what fields are in common
+-- across all types.
+data InterfaceType m = InterfaceType
+    Name (Maybe Text) [InterfaceType m] (HashMap Name (Field m))
+
+instance forall a. Eq (InterfaceType a) where
+    (InterfaceType this _ _ _) == (InterfaceType that _ _ _) = this == that
+
+-- | Union Type Definition.
+--
+-- When a field can return one of a heterogeneous set of types, a Union type is
+-- used to describe what types are possible.
+data UnionType m = UnionType Name (Maybe Text) [ObjectType m]
+
+instance forall a. Eq (UnionType a) where
+    (UnionType this _ _) == (UnionType that _ _) = this == that
+
+-- | Output object field definition.
+data Field m = Field
+    (Maybe Text) -- ^ Description.
+    (Type m) -- ^ Field type.
+    In.Arguments -- ^ Arguments.
+
+-- | These types may be used as output types as the result of fields.
+--
+-- GraphQL distinguishes between "wrapping" and "named" types. Each wrapping
+-- type can wrap other wrapping or named types. Wrapping types are lists and
+-- Non-Null types (named types are nullable by default).
+data Type m
+    = NamedScalarType ScalarType
+    | NamedEnumType EnumType
+    | NamedObjectType (ObjectType m)
+    | NamedInterfaceType (InterfaceType m)
+    | NamedUnionType (UnionType m)
+    | ListType (Type m)
+    | NonNullScalarType ScalarType
+    | NonNullEnumType EnumType
+    | NonNullObjectType (ObjectType m)
+    | NonNullInterfaceType (InterfaceType m)
+    | NonNullUnionType (UnionType m)
+    | NonNullListType (Type m)
+    deriving Eq
+
+-- | Matches either 'NamedScalarType' or 'NonNullScalarType'.
+pattern ScalarBaseType :: forall m. ScalarType -> Type m
+pattern ScalarBaseType scalarType <- (isScalarType -> Just scalarType)
+
+-- | Matches either 'NamedEnumType' or 'NonNullEnumType'.
+pattern EnumBaseType :: forall m. EnumType -> Type m
+pattern EnumBaseType enumType <- (isEnumType -> Just enumType)
+
+-- | Matches either 'NamedObjectType' or 'NonNullObjectType'.
+pattern ObjectBaseType :: forall m. ObjectType m -> Type m
+pattern ObjectBaseType objectType <- (isObjectType -> Just objectType)
+
+-- | Matches either 'NamedInterfaceType' or 'NonNullInterfaceType'.
+pattern InterfaceBaseType :: forall m. InterfaceType m -> Type m
+pattern InterfaceBaseType interfaceType <-
+    (isInterfaceType -> Just interfaceType)
+
+-- | Matches either 'NamedUnionType' or 'NonNullUnionType'.
+pattern UnionBaseType :: forall m. UnionType m -> Type m
+pattern UnionBaseType unionType <- (isUnionType -> Just unionType)
+
+-- | Matches either 'ListType' or 'NonNullListType'.
+pattern ListBaseType :: forall m. Type m -> Type m
+pattern ListBaseType listType <- (isListType -> Just listType)
+
+{-# COMPLETE ScalarBaseType
+    , EnumBaseType
+    , ObjectBaseType
+    , ListBaseType
+    , InterfaceBaseType
+    , UnionBaseType
+    #-}
+
+isScalarType :: forall m. Type m -> Maybe ScalarType
+isScalarType (NamedScalarType outputType) = Just outputType
+isScalarType (NonNullScalarType outputType) = Just outputType
+isScalarType _ = Nothing
+
+isObjectType :: forall m. Type m -> Maybe (ObjectType m)
+isObjectType (NamedObjectType outputType) = Just outputType
+isObjectType (NonNullObjectType outputType) = Just outputType
+isObjectType _ = Nothing
+
+isEnumType :: forall m. Type m -> Maybe EnumType
+isEnumType (NamedEnumType outputType) = Just outputType
+isEnumType (NonNullEnumType outputType) = Just outputType
+isEnumType _ = Nothing
+
+isInterfaceType :: forall m. Type m -> Maybe (InterfaceType m)
+isInterfaceType (NamedInterfaceType interfaceType) = Just interfaceType
+isInterfaceType (NonNullInterfaceType interfaceType) = Just interfaceType
+isInterfaceType _ = Nothing
+
+isUnionType :: forall m. Type m -> Maybe (UnionType m)
+isUnionType (NamedUnionType unionType) = Just unionType
+isUnionType (NonNullUnionType unionType) = Just unionType
+isUnionType _ = Nothing
+
+isListType :: forall m. Type m -> Maybe (Type m)
+isListType (ListType outputType) = Just outputType
+isListType (NonNullListType outputType) = Just outputType
+isListType _ = Nothing
+
+-- | Checks whether the given output type is a non-null type.
+isNonNullType :: forall m. Type m -> Bool
+isNonNullType (NonNullScalarType _) = True
+isNonNullType (NonNullEnumType _) = True
+isNonNullType (NonNullObjectType _) = True
+isNonNullType (NonNullInterfaceType _) = True
+isNonNullType (NonNullUnionType _) = True
+isNonNullType (NonNullListType _) = True
+isNonNullType _ = False
+
+-- | Resolution context holds resolver arguments and the root value.
+data Context = Context
+    { arguments :: Arguments
+    , values :: Value
+    }
+
+-- | Monad transformer stack used by the resolvers for determining the resolved
+-- value of a field.
+type Resolve m = ReaderT Context m Value
+
+-- | Monad transformer stack used by the resolvers for determining the resolved
+-- event stream of a subscription field.
+type Subscribe m = ReaderT Context m (SourceEventStream m)
+
+-- | A source stream represents the sequence of events, each of which will
+-- trigger a GraphQL execution corresponding to that event.
+type SourceEventStream m = ConduitT () Value m ()
+
+-- | 'Resolver' associates some function(s) with each 'Field'. 'ValueResolver'
+-- resolves a 'Field' into a 'Value'. 'EventStreamResolver' resolves
+-- additionally a 'Field' into a 'SourceEventStream' if it is the field of a
+-- root subscription type.
+--
+-- The resolvers aren't part of the 'Field' itself because not all fields
+-- have resolvers (interface fields don't have an implementation).
+data Resolver m
+    = ValueResolver (Field m) (Resolve m)
+    | EventStreamResolver (Field m) (Resolve m) (Subscribe m)
+
+-- | Retrieves an argument by its name. If the argument with this name couldn't
+-- be found, returns 'Null' (i.e. the argument is assumed to
+-- be optional then).
+argument :: Monad m => Name -> Resolve m
+argument argumentName = do
+    argumentValue <- asks $ lookupArgument . arguments
+    pure $ fromMaybe Null argumentValue
+  where
+    lookupArgument (Arguments argumentMap) =
+        HashMap.lookup argumentName argumentMap

src/Language/GraphQL/Type/Schema.hs

@@ -0,0 +1,155 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+-- | This module provides a representation of a @GraphQL@ Schema in addition to
+-- functions for defining and manipulating schemas.
+module Language.GraphQL.Type.Schema
+    ( schema
+    , module Language.GraphQL.Type.Internal
+    ) where
+
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Language.GraphQL.AST.DirectiveLocation (DirectiveLocation(..))
+import qualified Language.GraphQL.AST.DirectiveLocation as DirectiveLocation
+import qualified Language.GraphQL.AST as Full
+import Language.GraphQL.Type.Internal
+    ( Directive(..)
+    , Directives
+    , Schema
+    , Type(..)
+    , directives
+    , mutation
+    , subscription
+    , query
+    , types
+    )
+import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.Type.Internal as Internal
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+
+-- | Schema constructor.
+schema :: forall m
+    . Out.ObjectType m -- ^ Query type.
+    -> Maybe (Out.ObjectType m) -- ^ Mutation type.
+    -> Maybe (Out.ObjectType m) -- ^ Subscription type.
+    -> Directives -- ^ Directive definitions.
+    -> Schema m -- ^ Schema.
+schema queryRoot mutationRoot subscriptionRoot directiveDefinitions =
+    Internal.Schema queryRoot mutationRoot subscriptionRoot allDirectives collectedTypes
+  where
+    collectedTypes = collectReferencedTypes queryRoot mutationRoot subscriptionRoot
+    allDirectives = HashMap.union directiveDefinitions defaultDirectives
+    defaultDirectives = HashMap.fromList
+        [ ("skip", skipDirective)
+        , ("include", includeDirective)
+        , ("deprecated", deprecatedDirective)
+        ]
+    includeDirective =
+        Directive includeDescription skipIncludeLocations includeArguments
+    includeArguments = HashMap.singleton "if"
+        $ In.Argument (Just "Included when true.") ifType Nothing
+    includeDescription = Just
+        "Directs the executor to include this field or fragment only when the \
+        \`if` argument is true."
+    skipDirective = Directive skipDescription skipIncludeLocations skipArguments
+    skipArguments = HashMap.singleton "if"
+        $ In.Argument (Just "skipped when true.") ifType Nothing
+    ifType = In.NonNullScalarType Definition.boolean
+    skipDescription = Just
+        "Directs the executor to skip this field or fragment when the `if` \
+        \argument is true."
+    skipIncludeLocations =
+        [ ExecutableDirectiveLocation DirectiveLocation.Field
+        , ExecutableDirectiveLocation DirectiveLocation.FragmentSpread
+        , ExecutableDirectiveLocation DirectiveLocation.InlineFragment
+        ]
+    deprecatedDirective =
+        Directive deprecatedDescription deprecatedLocations deprecatedArguments
+    reasonDescription = Just
+        "Explains why this element was deprecated, usually also including a \
+        \suggestion for how to access supported similar data. Formatted using \
+        \the Markdown syntax, as specified by \
+        \[CommonMark](https://commonmark.org/).'"
+    deprecatedArguments = HashMap.singleton "reason"
+        $ In.Argument reasonDescription reasonType
+        $ Just "No longer supported"
+    reasonType = In.NamedScalarType Definition.string
+    deprecatedDescription = Just
+        "Marks an element of a GraphQL schema as no longer supported."
+    deprecatedLocations =
+        [ TypeSystemDirectiveLocation DirectiveLocation.FieldDefinition
+        , TypeSystemDirectiveLocation DirectiveLocation.ArgumentDefinition
+        , TypeSystemDirectiveLocation DirectiveLocation.InputFieldDefinition
+        , TypeSystemDirectiveLocation DirectiveLocation.EnumValue
+        ]
+
+-- | Traverses the schema and finds all referenced types.
+collectReferencedTypes :: forall m
+    . Out.ObjectType m
+    -> Maybe (Out.ObjectType m)
+    -> Maybe (Out.ObjectType m)
+    -> HashMap Full.Name (Type m)
+collectReferencedTypes queryRoot mutationRoot subscriptionRoot =
+    let queryTypes = traverseObjectType queryRoot HashMap.empty
+        mutationTypes = maybe queryTypes (`traverseObjectType` queryTypes)
+            mutationRoot
+     in maybe mutationTypes (`traverseObjectType` queryTypes) subscriptionRoot
+  where
+    collect traverser typeName element foundTypes
+        | HashMap.member typeName foundTypes = foundTypes
+        | otherwise = traverser $ HashMap.insert typeName element foundTypes
+    visitFields (Out.Field _ outputType arguments) foundTypes
+        = traverseOutputType outputType
+        $ foldr visitArguments foundTypes arguments
+    visitArguments (In.Argument _ inputType _) = traverseInputType inputType
+    visitInputFields (In.InputField _ inputType _) = traverseInputType inputType
+    getField (Out.ValueResolver field _) = field
+    getField (Out.EventStreamResolver field _ _) = field
+    traverseInputType (In.InputObjectBaseType objectType) =
+        let In.InputObjectType typeName _ inputFields = objectType
+            element = InputObjectType objectType
+            traverser = flip (foldr visitInputFields) inputFields
+         in collect traverser typeName element
+    traverseInputType (In.ListBaseType listType) =
+        traverseInputType listType
+    traverseInputType (In.ScalarBaseType scalarType) =
+        let Definition.ScalarType typeName _ = scalarType
+         in collect Prelude.id typeName (ScalarType scalarType)
+    traverseInputType (In.EnumBaseType enumType) =
+        let Definition.EnumType typeName _ _ = enumType
+         in collect Prelude.id typeName (EnumType enumType)
+    traverseOutputType (Out.ObjectBaseType objectType) =
+        traverseObjectType objectType
+    traverseOutputType (Out.InterfaceBaseType interfaceType) =
+        traverseInterfaceType interfaceType
+    traverseOutputType (Out.UnionBaseType unionType) =
+        let Out.UnionType typeName _ types' = unionType
+            traverser = flip (foldr traverseObjectType) types'
+         in collect traverser typeName (UnionType unionType)
+    traverseOutputType (Out.ListBaseType listType) =
+        traverseOutputType listType
+    traverseOutputType (Out.ScalarBaseType scalarType) =
+        let Definition.ScalarType typeName _ = scalarType
+         in collect Prelude.id typeName (ScalarType scalarType)
+    traverseOutputType (Out.EnumBaseType enumType) =
+        let Definition.EnumType typeName _ _ = enumType
+         in collect Prelude.id typeName (EnumType enumType)
+    traverseObjectType objectType foundTypes =
+        let Out.ObjectType typeName _ interfaces fields = objectType
+            element = ObjectType objectType
+            traverser = polymorphicTraverser interfaces (getField <$> fields)
+         in collect traverser typeName element foundTypes
+    traverseInterfaceType interfaceType foundTypes =
+        let Out.InterfaceType typeName _ interfaces fields = interfaceType
+            element = InterfaceType interfaceType
+            traverser = polymorphicTraverser interfaces fields
+         in collect traverser typeName element foundTypes
+    polymorphicTraverser interfaces fields
+        = flip (foldr visitFields) fields
+        . flip (foldr traverseInterfaceType) interfaces

src/Language/GraphQL/Validate.hs

@@ -0,0 +1,506 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+-- | GraphQL validator.
+module Language.GraphQL.Validate
+    ( Validation.Error(..)
+    , document
+    , module Language.GraphQL.Validate.Rules
+    ) where
+
+import Control.Monad (join)
+import Control.Monad.Trans.Class (MonadTrans(..))
+import Control.Monad.Trans.Reader (runReaderT)
+import Data.Foldable (toList)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Sequence (Seq(..), (><), (|>))
+import qualified Data.Sequence as Seq
+import Language.GraphQL.AST.DirectiveLocation (DirectiveLocation(..))
+import qualified Language.GraphQL.AST.DirectiveLocation as DirectiveLocation
+import qualified Language.GraphQL.AST.Document as Full
+import qualified Language.GraphQL.Type.Internal as Type
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+import Language.GraphQL.Type.Schema (Schema)
+import qualified Language.GraphQL.Type.Schema as Schema
+import Language.GraphQL.Validate.Rules
+import Language.GraphQL.Validate.Validation (Validation(Validation))
+import qualified Language.GraphQL.Validate.Validation as Validation
+
+type ApplySelectionRule m a
+    = HashMap Full.Name (Schema.Type m)
+    -> Validation.Rule m
+    -> Maybe (Out.Type m)
+    -> a
+    -> Seq (Validation.RuleT m)
+
+type ApplyRule m a = Validation.Rule m -> a -> Seq (Validation.RuleT m)
+
+-- | Validates a document and returns a list of found errors. If the returned
+-- list is empty, the document is valid.
+document :: forall m
+    . Schema m
+    -> [Validation.Rule m]
+    -> Full.Document
+    -> Seq Validation.Error
+document schema' rules' document' =
+    runReaderT reader context
+  where
+    context = Validation
+        { Validation.ast = document'
+        , Validation.schema = schema'
+        }
+    reader = do
+        rule' <- lift $ Seq.fromList rules'
+        join $ lift $ foldr (definition rule' context) Seq.empty document'
+
+definition :: Validation.Rule m
+    -> Validation m
+    -> Full.Definition
+    -> Seq (Validation.RuleT m)
+    -> Seq (Validation.RuleT m)
+definition (Validation.DefinitionRule rule) _ definition' accumulator =
+    accumulator |> rule definition'
+definition rule context (Full.ExecutableDefinition definition') accumulator =
+    accumulator >< executableDefinition rule context definition'
+definition rule context (Full.TypeSystemDefinition typeSystemDefinition' _) accumulator =
+    accumulator >< typeSystemDefinition context rule typeSystemDefinition'
+definition rule context (Full.TypeSystemExtension extension _) accumulator =
+    accumulator >< typeSystemExtension context rule extension
+
+typeSystemExtension :: forall m
+    . Validation m
+    -> ApplyRule m Full.TypeSystemExtension
+typeSystemExtension context rule = \case
+    Full.SchemaExtension extension -> schemaExtension context rule extension
+    Full.TypeExtension extension -> typeExtension context rule extension
+
+typeExtension :: forall m. Validation m -> ApplyRule m Full.TypeExtension
+typeExtension context rule = \case
+    Full.ScalarTypeExtension _ directives' ->
+        directives context rule scalarLocation directives'
+    Full.ObjectTypeFieldsDefinitionExtension _ _ directives' fields
+        -> directives context rule objectLocation directives'
+        >< foldMap (fieldDefinition context rule) fields
+    Full.ObjectTypeDirectivesExtension _ _ directives' ->
+        directives context rule objectLocation directives'
+    Full.ObjectTypeImplementsInterfacesExtension _ _ -> mempty
+    Full.InterfaceTypeFieldsDefinitionExtension _ directives' fields
+        -> directives context rule interfaceLocation directives'
+        >< foldMap (fieldDefinition context rule) fields
+    Full.InterfaceTypeDirectivesExtension _ directives' ->
+        directives context rule interfaceLocation directives'
+    Full.UnionTypeUnionMemberTypesExtension _ directives' _ ->
+        directives context rule unionLocation directives'
+    Full.UnionTypeDirectivesExtension _ directives' ->
+        directives context rule unionLocation directives'
+    Full.EnumTypeEnumValuesDefinitionExtension _ directives' values
+        -> directives context rule enumLocation directives'
+        >< foldMap (enumValueDefinition context rule) values
+    Full.EnumTypeDirectivesExtension _ directives' ->
+        directives context rule enumLocation directives'
+    Full.InputObjectTypeInputFieldsDefinitionExtension _ directives' fields
+        -> directives context rule inputObjectLocation directives'
+        >< foldMap forEachInputFieldDefinition fields
+    Full.InputObjectTypeDirectivesExtension _ directives' ->
+        directives context rule inputObjectLocation directives'
+  where
+    forEachInputFieldDefinition =
+        inputValueDefinition context rule inputFieldDefinitionLocation
+
+schemaExtension :: forall m. Validation m -> ApplyRule m Full.SchemaExtension
+schemaExtension context rule = \case
+    Full.SchemaOperationExtension directives' _ ->
+        directives context rule schemaLocation directives'
+    Full.SchemaDirectivesExtension directives' ->
+        directives context rule schemaLocation directives'
+
+schemaLocation :: DirectiveLocation
+schemaLocation = TypeSystemDirectiveLocation DirectiveLocation.Schema
+
+interfaceLocation :: DirectiveLocation
+interfaceLocation = TypeSystemDirectiveLocation DirectiveLocation.Interface
+
+objectLocation :: DirectiveLocation
+objectLocation = TypeSystemDirectiveLocation DirectiveLocation.Object
+
+unionLocation :: DirectiveLocation
+unionLocation = TypeSystemDirectiveLocation DirectiveLocation.Union
+
+enumLocation :: DirectiveLocation
+enumLocation = TypeSystemDirectiveLocation DirectiveLocation.Enum
+
+inputObjectLocation :: DirectiveLocation
+inputObjectLocation = TypeSystemDirectiveLocation DirectiveLocation.InputObject
+
+scalarLocation :: DirectiveLocation
+scalarLocation = TypeSystemDirectiveLocation DirectiveLocation.Scalar
+
+enumValueLocation :: DirectiveLocation
+enumValueLocation = TypeSystemDirectiveLocation DirectiveLocation.EnumValue
+
+fieldDefinitionLocation :: DirectiveLocation
+fieldDefinitionLocation =
+    TypeSystemDirectiveLocation DirectiveLocation.FieldDefinition
+
+inputFieldDefinitionLocation :: DirectiveLocation
+inputFieldDefinitionLocation =
+    TypeSystemDirectiveLocation DirectiveLocation.InputFieldDefinition
+
+argumentDefinitionLocation :: DirectiveLocation
+argumentDefinitionLocation =
+    TypeSystemDirectiveLocation DirectiveLocation.ArgumentDefinition
+
+queryLocation :: DirectiveLocation
+queryLocation = ExecutableDirectiveLocation DirectiveLocation.Query
+
+mutationLocation :: DirectiveLocation
+mutationLocation = ExecutableDirectiveLocation DirectiveLocation.Mutation
+
+subscriptionLocation :: DirectiveLocation
+subscriptionLocation =
+    ExecutableDirectiveLocation DirectiveLocation.Subscription
+
+fieldLocation :: DirectiveLocation
+fieldLocation = ExecutableDirectiveLocation DirectiveLocation.Field
+
+fragmentDefinitionLocation :: DirectiveLocation
+fragmentDefinitionLocation =
+    ExecutableDirectiveLocation DirectiveLocation.FragmentDefinition
+
+fragmentSpreadLocation :: DirectiveLocation
+fragmentSpreadLocation =
+    ExecutableDirectiveLocation DirectiveLocation.FragmentSpread
+
+inlineFragmentLocation :: DirectiveLocation
+inlineFragmentLocation =
+    ExecutableDirectiveLocation DirectiveLocation.InlineFragment
+
+executableDefinition :: forall m
+    . Validation.Rule m
+    -> Validation m
+    -> Full.ExecutableDefinition
+    -> Seq (Validation.RuleT m)
+executableDefinition rule context (Full.DefinitionOperation operation) =
+    operationDefinition rule context operation
+executableDefinition rule context (Full.DefinitionFragment fragment) =
+    fragmentDefinition rule context fragment
+
+typeSystemDefinition :: forall m
+    . Validation m
+    -> ApplyRule m Full.TypeSystemDefinition
+typeSystemDefinition context rule = \case
+    Full.SchemaDefinition directives' _ ->
+        directives context rule schemaLocation directives'
+    Full.TypeDefinition typeDefinition' ->
+        typeDefinition context rule typeDefinition'
+    Full.DirectiveDefinition _ _ arguments' _ ->
+        argumentsDefinition context rule arguments'
+
+typeDefinition :: forall m. Validation m -> ApplyRule m Full.TypeDefinition
+typeDefinition context rule = \case
+    Full.ScalarTypeDefinition _ _ directives' ->
+        directives context rule scalarLocation directives'
+    Full.ObjectTypeDefinition _ _ _ directives' fields
+        -> directives context rule objectLocation directives'
+         >< foldMap (fieldDefinition context rule) fields
+    Full.InterfaceTypeDefinition _ _ directives' fields
+        -> directives context rule interfaceLocation directives'
+        >< foldMap (fieldDefinition context rule) fields
+    Full.UnionTypeDefinition _ _ directives' _ ->
+        directives context rule unionLocation directives'
+    Full.EnumTypeDefinition _ _ directives' values
+        -> directives context rule enumLocation directives'
+        >< foldMap (enumValueDefinition context rule) values
+    Full.InputObjectTypeDefinition _ _ directives' fields
+        -> directives context rule inputObjectLocation directives'
+        <> foldMap forEachInputFieldDefinition fields
+  where
+    forEachInputFieldDefinition =
+        inputValueDefinition context rule inputFieldDefinitionLocation
+
+enumValueDefinition :: forall m
+    . Validation m
+    -> ApplyRule m Full.EnumValueDefinition
+enumValueDefinition context rule (Full.EnumValueDefinition _ _ directives') =
+    directives context rule enumValueLocation directives'
+
+fieldDefinition :: forall m. Validation m -> ApplyRule m Full.FieldDefinition
+fieldDefinition context rule (Full.FieldDefinition _ _ arguments' _ directives')
+    = directives context rule fieldDefinitionLocation directives'
+    >< argumentsDefinition context rule arguments'
+
+argumentsDefinition :: forall m
+    . Validation m
+    -> ApplyRule m Full.ArgumentsDefinition
+argumentsDefinition context rule (Full.ArgumentsDefinition definitions) =
+    foldMap forEachArgument definitions
+  where
+    forEachArgument =
+        inputValueDefinition context rule argumentDefinitionLocation
+
+inputValueDefinition :: forall m
+    . Validation m
+    -> Validation.Rule m
+    -> DirectiveLocation
+    -> Full.InputValueDefinition
+    -> Seq (Validation.RuleT m)
+inputValueDefinition context rule directiveLocation definition' =
+    let Full.InputValueDefinition _ _ _ _ directives' = definition'
+     in directives context rule directiveLocation directives'
+
+operationDefinition :: forall m
+    . Validation.Rule m
+    -> Validation m
+    -> Full.OperationDefinition
+    -> Seq (Validation.RuleT m)
+operationDefinition rule context operation
+    | Validation.OperationDefinitionRule operationRule <- rule =
+        pure $ operationRule operation
+    | Validation.VariablesRule variablesRule <- rule
+    , Full.OperationDefinition _ _ variables _ _ _ <- operation =
+        foldMap (variableDefinition context rule) variables |> variablesRule variables
+    | Full.SelectionSet selections _ <- operation =
+        selectionSet context types' rule queryRoot selections
+    | Full.OperationDefinition Full.Query _ _ directives' selections _  <- operation
+        = selectionSet context types' rule queryRoot selections
+        >< directives context rule queryLocation directives'
+    | Full.OperationDefinition Full.Mutation _ _ directives' selections _  <- operation =
+        let root = Out.NamedObjectType <$> Schema.mutation schema'
+         in selectionSet context types' rule root selections
+        >< directives context rule mutationLocation directives'
+    | Full.OperationDefinition Full.Subscription _ _ directives' selections _  <- operation =
+        let root = Out.NamedObjectType <$> Schema.subscription schema'
+         in selectionSet context types' rule root selections
+        >< directives context rule subscriptionLocation directives'
+  where
+    schema' = Validation.schema context
+    queryRoot = Just $ Out.NamedObjectType $ Schema.query schema'
+    types' = Schema.types schema'
+        
+typeToOut :: forall m. Schema.Type m -> Maybe (Out.Type m)
+typeToOut (Schema.ObjectType objectType) =
+    Just $ Out.NamedObjectType objectType
+typeToOut (Schema.InterfaceType interfaceType) =
+    Just $ Out.NamedInterfaceType interfaceType
+typeToOut (Schema.UnionType unionType) = Just $ Out.NamedUnionType unionType
+typeToOut (Schema.EnumType enumType) = Just $ Out.NamedEnumType enumType
+typeToOut (Schema.ScalarType scalarType) = Just $ Out.NamedScalarType scalarType
+typeToOut _ = Nothing
+
+variableDefinition :: forall m
+    . Validation m
+    -> ApplyRule m Full.VariableDefinition
+variableDefinition context rule (Full.VariableDefinition _ typeName value' _)
+    | Just defaultValue' <- value'
+    , types <- Schema.types $ Validation.schema context
+    , variableType <- Type.lookupInputType typeName types =
+        constValue rule variableType defaultValue'
+variableDefinition _ _ _ = mempty
+
+constValue :: forall m
+    . Validation.Rule m
+    -> Maybe In.Type
+    -> Full.Node Full.ConstValue
+    -> Seq (Validation.RuleT m)
+constValue (Validation.ValueRule _ rule) valueType = go valueType
+  where
+    go inputObjectType value'@(Full.Node (Full.ConstObject fields) _)
+        = foldMap (forEach inputObjectType) (Seq.fromList fields)
+        |> rule inputObjectType value'
+    go listType value'@(Full.Node (Full.ConstList values) location')
+        = embedListLocation go listType values location'
+        |> rule listType value'
+    go anotherValue value' = pure $ rule anotherValue value'
+    forEach inputObjectType Full.ObjectField{value = value', ..} =
+        go (valueTypeByName name inputObjectType) value'
+constValue _ _ = const mempty
+
+inputFieldType :: In.InputField -> In.Type
+inputFieldType (In.InputField _ inputFieldType' _) = inputFieldType'
+
+valueTypeByName :: Full.Name -> Maybe In.Type -> Maybe In.Type
+valueTypeByName fieldName (Just( In.InputObjectBaseType inputObjectType)) =
+    let In.InputObjectType _ _ fieldTypes = inputObjectType
+     in inputFieldType <$> HashMap.lookup fieldName fieldTypes
+valueTypeByName _ _ = Nothing
+
+fragmentDefinition :: forall m
+    . Validation.Rule m
+    -> Validation m
+    -> Full.FragmentDefinition
+    -> Seq (Validation.RuleT m)
+fragmentDefinition (Validation.FragmentDefinitionRule rule) _ definition' =
+    pure $ rule definition'
+fragmentDefinition rule context definition'
+    | Full.FragmentDefinition _ typeCondition directives' selections _ <- definition'
+    , Validation.FragmentRule definitionRule _ <- rule
+        = applyToChildren typeCondition directives' selections
+        |> definitionRule definition'
+    | Full.FragmentDefinition _ typeCondition directives' selections _ <- definition'
+        = applyToChildren typeCondition directives' selections
+  where
+    types' = Schema.types $ Validation.schema context
+    applyToChildren typeCondition directives' selections
+        = selectionSet context types' rule (lookupType' typeCondition) selections
+        >< directives context rule fragmentDefinitionLocation directives'
+    lookupType' = flip lookupType types'
+
+lookupType :: forall m
+    . Full.TypeCondition
+    -> HashMap Full.Name (Schema.Type m)
+    -> Maybe (Out.Type m)
+lookupType typeCondition types' = HashMap.lookup typeCondition types'
+    >>= typeToOut
+
+selectionSet :: Traversable t
+    => forall m
+    . Validation m
+    -> ApplySelectionRule m (t Full.Selection)
+selectionSet context types' rule = foldMap . selection context types' rule
+
+selection :: forall m. Validation m -> ApplySelectionRule m Full.Selection
+selection context types' rule objectType selection'
+    | Validation.SelectionRule selectionRule <- rule =
+        applyToChildren |> selectionRule objectType selection'
+    | otherwise = applyToChildren
+  where
+    applyToChildren =
+        case selection' of
+            Full.FieldSelection field' ->
+                field context types' rule objectType field'
+            Full.InlineFragmentSelection inlineFragment' ->
+                inlineFragment context types' rule objectType inlineFragment'
+            Full.FragmentSpreadSelection fragmentSpread' ->
+                fragmentSpread context rule fragmentSpread'
+
+field :: forall m. Validation m -> ApplySelectionRule m Full.Field
+field context types' rule objectType field' = go field'
+  where
+    go (Full.Field _ fieldName _ _ _ _)
+        | Validation.FieldRule fieldRule <- rule =
+            applyToChildren fieldName |> fieldRule objectType field'
+        | Validation.ArgumentsRule argumentsRule _  <- rule =
+            applyToChildren fieldName |> argumentsRule objectType field'
+        | otherwise = applyToChildren fieldName
+    typeFieldType (Out.Field _ type' _) = type'
+    typeFieldArguments (Out.Field _ _ argumentTypes) = argumentTypes
+    applyToChildren fieldName =
+        let Full.Field _ _ arguments' directives' selections _ = field'
+            typeField = objectType >>= Type.lookupTypeField fieldName
+            argumentTypes = maybe mempty typeFieldArguments typeField
+         in selectionSet context types' rule (typeFieldType <$> typeField) selections
+            >< directives context rule fieldLocation directives'
+            >< arguments rule argumentTypes arguments'
+
+arguments :: forall m
+    . Validation.Rule m
+    -> In.Arguments
+    -> [Full.Argument]
+    -> Seq (Validation.RuleT m)
+arguments rule argumentTypes = foldMap forEach . Seq.fromList
+  where
+    forEach argument'@(Full.Argument argumentName _ _) = 
+       let argumentType = HashMap.lookup argumentName argumentTypes
+        in argument rule argumentType argument'
+
+argument :: forall m
+    . Validation.Rule m
+    -> Maybe In.Argument
+    -> Full.Argument
+    -> Seq (Validation.RuleT m)
+argument rule argumentType (Full.Argument _ value' _) =
+    value rule (valueType <$> argumentType) value'
+  where
+    valueType (In.Argument _ valueType' _) = valueType'
+
+-- valueTypeFromList :: Maybe In.Type -> Maybe In.Type
+embedListLocation :: forall a m
+    . (Maybe In.Type -> Full.Node a -> Seq m)
+    -> Maybe In.Type
+    -> [a]
+    -> Full.Location
+    -> Seq m
+embedListLocation go listType values location'
+    = foldMap (go $ valueTypeFromList listType) 
+    $ flip Full.Node location' <$> Seq.fromList values
+  where
+    valueTypeFromList (Just (In.ListBaseType baseType)) = Just baseType
+    valueTypeFromList _ = Nothing
+
+value :: forall m
+    . Validation.Rule m
+    -> Maybe In.Type
+    -> Full.Node Full.Value
+    -> Seq (Validation.RuleT m)
+value (Validation.ValueRule rule _) valueType = go valueType
+  where
+    go inputObjectType value'@(Full.Node (Full.Object fields) _)
+        = foldMap (forEach inputObjectType) (Seq.fromList fields)
+        |> rule inputObjectType value'
+    go listType value'@(Full.Node (Full.List values) location')
+        = embedListLocation go listType values location'
+        |> rule listType value'
+    go anotherValue value' = pure $ rule anotherValue value'
+    forEach inputObjectType Full.ObjectField{value = value', ..} =
+        go (valueTypeByName name inputObjectType) value'
+value _ _ = const mempty
+
+inlineFragment :: forall m
+    . Validation m
+    -> ApplySelectionRule m Full.InlineFragment
+inlineFragment context types' rule objectType inlineFragment' =
+    go inlineFragment'
+  where
+    go (Full.InlineFragment optionalType directives' selections _)
+        | Validation.FragmentRule _ fragmentRule <- rule
+            = applyToChildren (refineTarget optionalType) directives' selections
+            |> fragmentRule inlineFragment'
+        | otherwise = applyToChildren (refineTarget optionalType) directives' selections
+    refineTarget (Just typeCondition) = lookupType typeCondition types'
+    refineTarget Nothing = objectType
+    applyToChildren objectType' directives' selections
+        = selectionSet context types' rule objectType' selections
+        >< directives context rule inlineFragmentLocation directives'
+
+fragmentSpread :: forall m. Validation m -> ApplyRule m Full.FragmentSpread
+fragmentSpread context rule fragmentSpread'@(Full.FragmentSpread _ directives' _)
+    | Validation.FragmentSpreadRule fragmentRule <- rule =
+        applyToChildren |> fragmentRule fragmentSpread'
+    | otherwise = applyToChildren
+  where
+    applyToChildren = directives context rule fragmentSpreadLocation directives'
+
+directives :: Traversable t
+    => forall m
+    . Validation m
+    -> Validation.Rule m
+    -> DirectiveLocation
+    -> t Full.Directive
+    -> Seq (Validation.RuleT m)
+directives context rule directiveLocation directives'
+    | Validation.DirectivesRule directivesRule <- rule =
+        applyToChildren |> directivesRule directiveLocation directiveList
+    | otherwise = applyToChildren
+  where
+    directiveList = toList directives'
+    applyToChildren = foldMap (directive context rule) directiveList
+
+directive :: forall m. Validation m -> ApplyRule m Full.Directive
+directive _ (Validation.ArgumentsRule _ argumentsRule) directive' =
+    pure $ argumentsRule directive'
+directive context rule (Full.Directive directiveName arguments' _) =
+    let argumentTypes = maybe HashMap.empty directiveArguments
+            $ HashMap.lookup directiveName
+            $ Schema.directives
+            $ Validation.schema context
+     in arguments rule argumentTypes arguments'
+  where
+    directiveArguments (Schema.Directive _ _ argumentTypes) = argumentTypes

src/Language/GraphQL/Validate/Validation.hs

@@ -0,0 +1,50 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+-- | Definitions used by the validation rules and the validator itself.
+module Language.GraphQL.Validate.Validation
+    ( Error(..)
+    , Rule(..)
+    , RuleT
+    , Validation(..)
+    ) where
+
+import Control.Monad.Trans.Reader (ReaderT)
+import Data.Sequence (Seq)
+import Language.GraphQL.AST.DirectiveLocation (DirectiveLocation(..))
+import Language.GraphQL.AST.Document
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+import Language.GraphQL.Type.Schema (Schema)
+
+-- | Validation error.
+data Error = Error
+    { message :: String
+    , locations :: [Location]
+    } deriving (Eq, Show)
+
+-- | Validation rule context.
+data Validation m = Validation
+    { ast :: Document
+    , schema :: Schema m
+    }
+
+-- | 'Rule' assigns a function to each AST node that can be validated. If the
+-- validation fails, the function should return an error message, or 'Nothing'
+-- otherwise.
+data Rule m
+    = DefinitionRule (Definition -> RuleT m)
+    | OperationDefinitionRule (OperationDefinition -> RuleT m)
+    | FragmentDefinitionRule (FragmentDefinition -> RuleT m)
+    | SelectionRule (Maybe (Out.Type m) -> Selection -> RuleT m)
+    | FragmentRule (FragmentDefinition -> RuleT m) (InlineFragment -> RuleT m)
+    | FragmentSpreadRule (FragmentSpread -> RuleT m)
+    | FieldRule (Maybe (Out.Type m) -> Field -> RuleT m)
+    | ArgumentsRule (Maybe (Out.Type m) -> Field -> RuleT m) (Directive -> RuleT m)
+    | DirectivesRule (DirectiveLocation -> [Directive] -> RuleT m)
+    | VariablesRule ([VariableDefinition] -> RuleT m)
+    | ValueRule (Maybe In.Type -> Node Value -> RuleT m) (Maybe In.Type -> Node ConstValue -> RuleT m)
+
+-- | Monad transformer used by the rules.
+type RuleT m = ReaderT (Validation m) Seq Error

src/Test/Hspec/GraphQL.hs

@@ -0,0 +1,41 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE ExplicitForAll #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+-- | Test helpers.
+module Test.Hspec.GraphQL
+    ( shouldResolve
+    , shouldResolveTo
+    ) where
+
+import Control.Monad.Catch (MonadCatch)
+import qualified Data.Aeson as Aeson
+import qualified Data.HashMap.Strict as HashMap
+import Data.Text (Text)
+import Language.GraphQL.Error
+import Test.Hspec.Expectations (Expectation, expectationFailure, shouldBe, shouldNotSatisfy)
+
+-- | Asserts that a query resolves to some value.
+shouldResolveTo :: MonadCatch m
+    => Either (ResponseEventStream m Aeson.Value) Aeson.Object
+    -> Aeson.Object
+    -> Expectation
+shouldResolveTo (Right actual) expected = actual `shouldBe` expected
+shouldResolveTo _ _ = expectationFailure
+    "the query is expected to resolve to a value, but it resolved to an event stream"
+
+-- | Asserts that the response doesn't contain any errors.
+shouldResolve :: MonadCatch m
+    => (Text -> IO (Either (ResponseEventStream m Aeson.Value) Aeson.Object))
+    -> Text
+    -> Expectation
+shouldResolve executor query = do
+    actual <- executor query
+    case actual of
+        Right response ->
+            response `shouldNotSatisfy` HashMap.member "errors"
+        _ -> expectationFailure
+            "the query is expected to resolve to a value, but it resolved to an event stream"

stack.yaml

@@ -1,4 +1,4 @@
-resolver: lts-15.12
+resolver: lts-16.20
 
 packages:
 - .
@@ -6,4 +6,4 @@ packages:
 extra-deps: []
 flags: {}
 
-pvp-bounds: both
+pvp-bounds: lower

tests/Language/GraphQL/AST/EncoderSpec.hs

@@ -4,7 +4,7 @@ module Language.GraphQL.AST.EncoderSpec
     ( spec
     ) where
 
-import Language.GraphQL.AST
+import qualified Language.GraphQL.AST.Document as Full
 import Language.GraphQL.AST.Encoder
 import Test.Hspec (Spec, context, describe, it, shouldBe, shouldStartWith, shouldEndWith, shouldNotContain)
 import Test.QuickCheck (choose, oneof, forAll)
@@ -15,52 +15,52 @@ spec :: Spec
 spec = do
     describe "value" $ do
         context "null value" $ do
-            let testNull formatter = value formatter Null `shouldBe` "null"
+            let testNull formatter = value formatter Full.Null `shouldBe` "null"
             it "minified" $ testNull minified
             it "pretty" $ testNull pretty
 
         context "minified" $ do
             it "escapes \\" $
-                value minified (String "\\") `shouldBe` "\"\\\\\""
+                value minified (Full.String "\\") `shouldBe` "\"\\\\\""
             it "escapes double quotes" $
-                value minified (String "\"") `shouldBe` "\"\\\"\""
+                value minified (Full.String "\"") `shouldBe` "\"\\\"\""
             it "escapes \\f" $
-                value minified (String "\f") `shouldBe` "\"\\f\""
+                value minified (Full.String "\f") `shouldBe` "\"\\f\""
             it "escapes \\n" $
-                value minified (String "\n") `shouldBe` "\"\\n\""
+                value minified (Full.String "\n") `shouldBe` "\"\\n\""
             it "escapes \\r" $
-                value minified (String "\r") `shouldBe` "\"\\r\""
+                value minified (Full.String "\r") `shouldBe` "\"\\r\""
             it "escapes \\t" $
-                value minified (String "\t") `shouldBe` "\"\\t\""
+                value minified (Full.String "\t") `shouldBe` "\"\\t\""
             it "escapes backspace" $
-                value minified (String "a\bc") `shouldBe` "\"a\\bc\""
+                value minified (Full.String "a\bc") `shouldBe` "\"a\\bc\""
             context "escapes Unicode for chars less than 0010" $ do
-                it "Null" $ value minified (String "\x0000") `shouldBe` "\"\\u0000\""
-                it "bell" $ value minified (String "\x0007") `shouldBe` "\"\\u0007\""
+                it "Null" $ value minified (Full.String "\x0000") `shouldBe` "\"\\u0000\""
+                it "bell" $ value minified (Full.String "\x0007") `shouldBe` "\"\\u0007\""
             context "escapes Unicode for char less than 0020" $ do
-                it "DLE" $ value minified (String "\x0010") `shouldBe` "\"\\u0010\""
-                it "EM" $ value minified (String "\x0019") `shouldBe` "\"\\u0019\""
+                it "DLE" $ value minified (Full.String "\x0010") `shouldBe` "\"\\u0010\""
+                it "EM" $ value minified (Full.String "\x0019") `shouldBe` "\"\\u0019\""
             context "encodes without escape" $ do
-                it "space" $ value minified (String "\x0020") `shouldBe` "\" \""
-                it "~" $ value minified (String "\x007E") `shouldBe` "\"~\""
+                it "space" $ value minified (Full.String "\x0020") `shouldBe` "\" \""
+                it "~" $ value minified (Full.String "\x007E") `shouldBe` "\"~\""
 
         context "pretty" $ do
             it "uses strings for short string values" $
-                value pretty (String "Short text") `shouldBe` "\"Short text\""
+                value pretty (Full.String "Short text") `shouldBe` "\"Short text\""
             it "uses block strings for text with new lines, with newline symbol" $
-                value pretty (String "Line 1\nLine 2")
+                value pretty (Full.String "Line 1\nLine 2")
                     `shouldBe` [r|"""
   Line 1
   Line 2
 """|]
             it "uses block strings for text with new lines, with CR symbol" $
-                value pretty (String "Line 1\rLine 2")
+                value pretty (Full.String "Line 1\rLine 2")
                     `shouldBe` [r|"""
   Line 1
   Line 2
 """|]
             it "uses block strings for text with new lines, with CR symbol followed by newline" $
-                value pretty (String "Line 1\r\nLine 2")
+                value pretty (Full.String "Line 1\r\nLine 2")
                     `shouldBe` [r|"""
   Line 1
   Line 2
@@ -77,12 +77,12 @@ spec = do
                 forAll genNotAllowedSymbol $ \x -> do
                     let
                       rawValue = "Short \n" <> cons x "text"
-                      encoded = value pretty (String $ toStrict rawValue)
+                      encoded = value pretty (Full.String $ toStrict rawValue)
                     shouldStartWith (unpack encoded) "\""
                     shouldEndWith (unpack encoded) "\""
                     shouldNotContain (unpack encoded) "\"\"\""
 
-            it "Hello world" $ value pretty (String "Hello,\n  World!\n\nYours,\n  GraphQL.")
+            it "Hello world" $ value pretty (Full.String "Hello,\n  World!\n\nYours,\n  GraphQL.")
               `shouldBe` [r|"""
   Hello,
     World!
@@ -91,29 +91,29 @@ spec = do
     GraphQL.
 """|]
 
-            it "has only newlines" $ value pretty (String "\n") `shouldBe` [r|"""
+            it "has only newlines" $ value pretty (Full.String "\n") `shouldBe` [r|"""
 
 
 """|]
             it "has newlines and one symbol at the begining" $
-              value pretty (String "a\n\n") `shouldBe` [r|"""
+              value pretty (Full.String "a\n\n") `shouldBe` [r|"""
   a
 
 
 """|]
             it "has newlines and one symbol at the end" $
-              value pretty (String "\n\na") `shouldBe` [r|"""
+              value pretty (Full.String "\n\na") `shouldBe` [r|"""
 
 
   a
 """|]
             it "has newlines and one symbol in the middle" $
-              value pretty (String "\na\n") `shouldBe` [r|"""
+              value pretty (Full.String "\na\n") `shouldBe` [r|"""
 
   a
 
 """|]
-            it "skip trailing whitespaces" $ value pretty (String "  Short\ntext    ")
+            it "skip trailing whitespaces" $ value pretty (Full.String "  Short\ntext    ")
               `shouldBe` [r|"""
   Short
   text
@@ -121,9 +121,13 @@ spec = do
 
     describe "definition" $
         it "indents block strings in arguments" $
-            let arguments = [Argument "message" (String "line1\nline2")]
-                field = Field Nothing "field" arguments [] []
-                operation = DefinitionOperation $ SelectionSet $ pure field
+            let location = Full.Location 0 0
+                argumentValue = Full.Node (Full.String "line1\nline2") location
+                arguments = [Full.Argument "message" argumentValue location]
+                field = Full.Field Nothing "field" arguments [] [] location
+                fieldSelection = pure $ Full.FieldSelection field
+                operation = Full.DefinitionOperation
+                    $ Full.SelectionSet fieldSelection location
              in definition pretty operation `shouldBe` [r|{
   field(message: """
     line1

tests/Language/GraphQL/AST/LexerSpec.hs

@@ -75,9 +75,9 @@ spec = describe "Lexer" $ do
             parse dollar "" "$" `shouldParse` "$"
             runBetween parens `shouldSucceedOn` "()"
             parse spread "" "..." `shouldParse` "..."
-            parse colon "" ":" `shouldParse` ":"
+            parse colon "" `shouldSucceedOn` ":"
             parse equals "" "=" `shouldParse` "="
-            parse at "" "@" `shouldParse` "@"
+            parse at "" `shouldSucceedOn` "@"
             runBetween brackets `shouldSucceedOn` "[]"
             runBetween braces `shouldSucceedOn` "{}"
             parse pipe "" "|" `shouldParse` "|"

tests/Language/GraphQL/AST/ParserSpec.hs

@@ -8,7 +8,7 @@ import Data.List.NonEmpty (NonEmpty(..))
 import Language.GraphQL.AST.Document
 import Language.GraphQL.AST.Parser
 import Test.Hspec (Spec, describe, it)
-import Test.Hspec.Megaparsec (shouldParse, shouldSucceedOn)
+import Test.Hspec.Megaparsec (shouldParse, shouldFailOn, shouldSucceedOn)
 import Text.Megaparsec (parse)
 import Text.RawString.QQ (r)
 
@@ -128,11 +128,12 @@ spec = describe "Parser" $ do
         parse document "" `shouldSucceedOn` [r|extend schema { query: Query }|]
 
     it "parses schema extension with an operation type and directive" $
-        let newDirective = Directive "newDirective" []
-            testSchemaExtension = TypeSystemExtension
-                $ SchemaExtension
+        let newDirective = Directive "newDirective" [] $ Location 1 15
+            schemaExtension = SchemaExtension
                 $ SchemaOperationExtension [newDirective]
                 $ OperationTypeDefinition Query "Query" :| []
+            testSchemaExtension = TypeSystemExtension schemaExtension
+                $ Location 1 1
             query = [r|extend schema @newDirective { query: Query }|]
          in parse document "" query `shouldParse` (testSchemaExtension :| [])
 
@@ -141,4 +142,30 @@ spec = describe "Parser" $ do
             extend type Story {
               isHiddenLocally: Boolean
             }
-        |]
+        |]
+
+    it "rejects variables in DefaultValue" $
+        parse document "" `shouldFailOn` [r|
+            query ($book: String = "Zarathustra", $author: String = $book) {
+              title
+            }
+        |]
+
+    it "parses documents beginning with a comment" $
+        parse document "" `shouldSucceedOn` [r|
+            """
+            Query
+            """
+            type Query {
+                queryField: String
+            }
+        |]
+
+    it "parses subscriptions" $
+        parse document "" `shouldSucceedOn` [r|
+            subscription NewMessages {
+              newMessage(roomId: 123) {
+                sender
+              }
+            }
+        |]

tests/Language/GraphQL/ErrorSpec.hs

@@ -1,9 +1,14 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 module Language.GraphQL.ErrorSpec
     ( spec
     ) where
 
 import qualified Data.Aeson as Aeson
+import qualified Data.Sequence as Seq
 import Language.GraphQL.Error
 import Test.Hspec ( Spec
                   , describe
@@ -14,11 +19,6 @@ import Test.Hspec ( Spec
 spec :: Spec
 spec = describe "singleError" $
     it "constructs an error with the given message" $
-        let expected = Aeson.object
-                [
-                    ("errors", Aeson.toJSON
-                        [ Aeson.object [("message", "Message.")]
-                        ]
-                    )
-                ]
+        let errors'' = Seq.singleton $ Error "Message." [] []
+            expected = Response Aeson.Null errors''
          in singleError "Message." `shouldBe` expected

tests/Language/GraphQL/Execute/CoerceSpec.hs

@@ -0,0 +1,126 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE OverloadedStrings #-}
+module Language.GraphQL.Execute.CoerceSpec
+    ( spec
+    ) where
+
+import Data.Aeson as Aeson ((.=))
+import qualified Data.Aeson as Aeson
+import qualified Data.Aeson.Types as Aeson
+import qualified Data.HashMap.Strict as HashMap
+import Data.Maybe (isNothing)
+import Data.Scientific (scientific)
+import qualified Language.GraphQL.Execute.Coerce as Coerce
+import Language.GraphQL.Type
+import qualified Language.GraphQL.Type.In as In
+import Prelude hiding (id)
+import Test.Hspec (Spec, describe, it, shouldBe, shouldSatisfy)
+
+direction :: EnumType
+direction = EnumType "Direction" Nothing  $ HashMap.fromList
+    [ ("NORTH", EnumValue Nothing)
+    , ("EAST", EnumValue Nothing)
+    , ("SOUTH", EnumValue Nothing)
+    , ("WEST", EnumValue Nothing)
+    ]
+
+singletonInputObject :: In.Type
+singletonInputObject = In.NamedInputObjectType type'
+  where
+    type' = In.InputObjectType "ObjectName" Nothing inputFields
+    inputFields = HashMap.singleton "field" field
+    field = In.InputField Nothing (In.NamedScalarType string) Nothing
+
+namedIdType :: In.Type
+namedIdType = In.NamedScalarType id
+
+spec :: Spec
+spec = do
+    describe "VariableValue Aeson" $ do
+        it "coerces strings" $
+            let expected = Just (String "asdf")
+                actual = Coerce.coerceVariableValue
+                    (In.NamedScalarType string) (Aeson.String "asdf")
+             in actual `shouldBe` expected
+        it "coerces non-null strings" $
+            let expected = Just (String "asdf")
+                actual = Coerce.coerceVariableValue
+                    (In.NonNullScalarType string) (Aeson.String "asdf")
+             in actual `shouldBe` expected
+        it "coerces booleans" $
+            let expected = Just (Boolean True)
+                actual = Coerce.coerceVariableValue
+                    (In.NamedScalarType boolean) (Aeson.Bool True)
+             in actual `shouldBe` expected
+        it "coerces zero to an integer" $
+            let expected = Just (Int 0)
+                actual = Coerce.coerceVariableValue
+                    (In.NamedScalarType int) (Aeson.Number 0)
+             in actual `shouldBe` expected
+        it "rejects fractional if an integer is expected" $
+            let actual = Coerce.coerceVariableValue
+                    (In.NamedScalarType int) (Aeson.Number $ scientific 14 (-1))
+             in actual `shouldSatisfy` isNothing
+        it "coerces float numbers" $
+            let expected = Just (Float 1.4)
+                actual = Coerce.coerceVariableValue
+                    (In.NamedScalarType float) (Aeson.Number $ scientific 14 (-1))
+             in actual `shouldBe` expected
+        it "coerces IDs" $
+            let expected = Just (String "1234")
+                json = Aeson.String "1234"
+                actual = Coerce.coerceVariableValue namedIdType json
+             in actual `shouldBe` expected
+        it "coerces input objects" $
+            let actual = Coerce.coerceVariableValue singletonInputObject
+                    $ Aeson.object ["field" .= ("asdf" :: Aeson.Value)]
+                expected = Just $ Object $ HashMap.singleton "field" "asdf"
+             in actual `shouldBe` expected
+        it "skips the field if it is missing in the variables" $
+            let actual = Coerce.coerceVariableValue
+                    singletonInputObject Aeson.emptyObject
+                expected = Just $ Object HashMap.empty
+             in actual `shouldBe` expected
+        it "fails if input object value contains extra fields" $
+            let actual = Coerce.coerceVariableValue singletonInputObject
+                    $ Aeson.object variableFields
+                variableFields =
+                    [ "field" .= ("asdf" :: Aeson.Value)
+                    , "extra" .= ("qwer" :: Aeson.Value)
+                    ]
+             in actual `shouldSatisfy` isNothing
+        it "preserves null" $
+            let actual = Coerce.coerceVariableValue namedIdType Aeson.Null
+             in actual `shouldBe` Just Null
+        it "preserves list order" $
+            let list = Aeson.toJSONList ["asdf" :: Aeson.Value, "qwer"]
+                listType = (In.ListType $ In.NamedScalarType string)
+                actual = Coerce.coerceVariableValue listType list
+                expected = Just $ List [String "asdf", String "qwer"]
+             in actual `shouldBe` expected
+
+    describe "coerceInputLiteral" $ do
+        it "coerces enums" $
+            let expected = Just (Enum "NORTH")
+                actual = Coerce.coerceInputLiteral
+                    (In.NamedEnumType direction) (Enum "NORTH")
+             in actual `shouldBe` expected
+        it "fails with non-existing enum value" $
+            let actual = Coerce.coerceInputLiteral
+                    (In.NamedEnumType direction) (Enum "NORTH_EAST")
+             in actual `shouldSatisfy` isNothing
+        it "coerces integers to IDs" $
+            let expected = Just (String "1234")
+                actual = Coerce.coerceInputLiteral namedIdType (Int 1234)
+             in actual `shouldBe` expected
+        it "coerces nulls" $ do
+            let actual = Coerce.coerceInputLiteral namedIdType Null
+             in actual `shouldBe` Just Null
+        it "wraps singleton lists" $ do
+            let expected = Just $ List [List [String "1"]]
+                embeddedType = In.ListType $ In.ListType namedIdType
+                actual = Coerce.coerceInputLiteral embeddedType (String "1")
+             in actual `shouldBe` expected

tests/Language/GraphQL/ExecuteSpec.hs

@@ -0,0 +1,132 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+module Language.GraphQL.ExecuteSpec
+    ( spec
+    ) where
+
+import Control.Exception (SomeException)
+import Data.Aeson ((.=))
+import qualified Data.Aeson as Aeson
+import Data.Aeson.Types (emptyObject)
+import Data.Conduit
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Language.GraphQL.AST (Document, Name)
+import Language.GraphQL.AST.Parser (document)
+import Language.GraphQL.Error
+import Language.GraphQL.Execute
+import Language.GraphQL.Type as Type
+import Language.GraphQL.Type.Out as Out
+import Test.Hspec (Spec, context, describe, it, shouldBe)
+import Text.Megaparsec (parse)
+import Text.RawString.QQ (r)
+
+philosopherSchema :: Schema (Either SomeException)
+philosopherSchema = schema queryType Nothing (Just subscriptionType) mempty
+
+queryType :: Out.ObjectType (Either SomeException)
+queryType = Out.ObjectType "Query" Nothing []
+    $ HashMap.singleton "philosopher" 
+    $ ValueResolver philosopherField
+    $ pure $ Type.Object mempty
+  where
+    philosopherField =
+        Out.Field Nothing (Out.NonNullObjectType philosopherType) HashMap.empty
+
+philosopherType :: Out.ObjectType (Either SomeException)
+philosopherType = Out.ObjectType "Philosopher" Nothing []
+    $ HashMap.fromList resolvers
+  where
+    resolvers =
+        [ ("firstName", ValueResolver firstNameField firstNameResolver)
+        , ("lastName", ValueResolver lastNameField lastNameResolver)
+        ]
+    firstNameField =
+        Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+    firstNameResolver = pure $ Type.String "Friedrich"
+    lastNameField
+        = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+    lastNameResolver = pure $ Type.String "Nietzsche"
+
+subscriptionType :: Out.ObjectType (Either SomeException)
+subscriptionType = Out.ObjectType "Subscription" Nothing []
+    $ HashMap.singleton "newQuote"
+    $ EventStreamResolver quoteField (pure $ Type.Object mempty)
+    $ pure $ yield $ Type.Object mempty
+  where
+    quoteField =
+        Out.Field Nothing (Out.NonNullObjectType quoteType) HashMap.empty
+
+quoteType :: Out.ObjectType (Either SomeException)
+quoteType = Out.ObjectType "Quote" Nothing []
+    $ HashMap.singleton "quote"
+    $ ValueResolver quoteField
+    $ pure "Naturam expelles furca, tamen usque recurret."
+  where
+    quoteField =
+        Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+
+type EitherStreamOrValue = Either
+    (ResponseEventStream (Either SomeException) Aeson.Value)
+    (Response Aeson.Value)
+
+execute' :: Document -> Either SomeException EitherStreamOrValue
+execute' =
+    execute philosopherSchema Nothing (mempty :: HashMap Name Aeson.Value)
+
+spec :: Spec
+spec =
+    describe "execute" $ do
+        it "rejects recursive fragments" $
+            let sourceQuery = [r|
+              {
+                ...cyclicFragment
+              }
+
+              fragment cyclicFragment on Query {
+                ...cyclicFragment
+              }
+            |]
+                expected = Response emptyObject mempty
+                Right (Right actual) = either (pure . parseError) execute'
+                    $ parse document "" sourceQuery
+             in actual `shouldBe` expected
+
+        context "Query" $ do
+            it "skips unknown fields" $
+                let data'' = Aeson.object
+                        [ "philosopher" .= Aeson.object
+                            [ "firstName" .= ("Friedrich" :: String)
+                            ]
+                        ]
+                    expected = Response data'' mempty
+                    Right (Right actual) = either (pure . parseError) execute'
+                        $ parse document "" "{ philosopher { firstName surname } }"
+                in actual `shouldBe` expected
+            it "merges selections" $
+                let data'' = Aeson.object
+                        [ "philosopher" .= Aeson.object
+                            [ "firstName" .= ("Friedrich" :: String)
+                            , "lastName" .= ("Nietzsche" :: String)
+                            ]
+                        ]
+                    expected = Response data'' mempty
+                    Right (Right actual) = either (pure . parseError) execute'
+                        $ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
+                in actual `shouldBe` expected
+        context "Subscription" $
+            it "subscribes" $
+                let data'' = Aeson.object
+                        [ "newQuote" .= Aeson.object
+                            [ "quote" .= ("Naturam expelles furca, tamen usque recurret." :: String)
+                            ]
+                        ]
+                    expected = Response data'' mempty
+                    Right (Left stream) = either (pure . parseError) execute'
+                        $ parse document "" "subscription { newQuote { quote } }"
+                    Right (Just actual) = runConduit $ stream .| await
+                in actual `shouldBe` expected

tests/Language/GraphQL/Type/OutSpec.hs

@@ -0,0 +1,18 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE OverloadedStrings #-}
+module Language.GraphQL.Type.OutSpec
+    ( spec
+    ) where
+
+import Language.GraphQL.Type
+import Test.Hspec (Spec, describe, it, shouldBe)
+
+spec :: Spec
+spec =
+    describe "Value" $
+        it "supports overloaded strings" $
+            let nietzsche = "Goldstaub abblasen." :: Value
+             in nietzsche `shouldBe` String "Goldstaub abblasen."

tests/Language/GraphQL/ValidateSpec.hs

@@ -0,0 +1,665 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+
+module Language.GraphQL.ValidateSpec
+    ( spec
+    ) where
+
+import Data.Foldable (toList)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Text (Text)
+import qualified Language.GraphQL.AST as AST
+import Language.GraphQL.Type
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type.Out as Out
+import Language.GraphQL.Validate
+import Test.Hspec (Spec, describe, it, shouldBe, shouldContain)
+import Text.Megaparsec (parse)
+import Text.RawString.QQ (r)
+
+petSchema :: Schema IO
+petSchema = schema queryType Nothing (Just subscriptionType) mempty
+
+queryType :: ObjectType IO
+queryType = ObjectType "Query" Nothing [] $ HashMap.fromList
+    [ ("dog", dogResolver)
+    , ("findDog", findDogResolver)
+    ]
+  where
+    dogField = Field Nothing (Out.NamedObjectType dogType) mempty
+    dogResolver = ValueResolver dogField $ pure Null
+    findDogArguments = HashMap.singleton "complex"
+        $ In.Argument Nothing (In.NonNullInputObjectType dogDataType) Nothing
+    findDogField = Field Nothing (Out.NamedObjectType dogType) findDogArguments
+    findDogResolver = ValueResolver findDogField $ pure Null
+
+dogCommandType :: EnumType
+dogCommandType = EnumType "DogCommand" Nothing $ HashMap.fromList
+    [ ("SIT", EnumValue Nothing)
+    , ("DOWN", EnumValue Nothing)
+    , ("HEEL", EnumValue Nothing)
+    ]
+
+dogType :: ObjectType IO
+dogType = ObjectType "Dog" Nothing [petType] $ HashMap.fromList
+    [ ("name", nameResolver)
+    , ("nickname", nicknameResolver)
+    , ("barkVolume", barkVolumeResolver)
+    , ("doesKnowCommand", doesKnowCommandResolver)
+    , ("isHousetrained", isHousetrainedResolver)
+    , ("owner", ownerResolver)
+    ]
+  where
+    nameField = Field Nothing (Out.NonNullScalarType string) mempty
+    nameResolver = ValueResolver nameField $ pure "Name"
+    nicknameField = Field Nothing (Out.NamedScalarType string) mempty
+    nicknameResolver = ValueResolver nicknameField $ pure "Nickname"
+    barkVolumeField = Field Nothing (Out.NamedScalarType int) mempty
+    barkVolumeResolver = ValueResolver barkVolumeField $ pure $ Int 3
+    doesKnowCommandField = Field Nothing (Out.NonNullScalarType boolean)
+        $ HashMap.singleton "dogCommand"
+        $ In.Argument Nothing (In.NonNullEnumType dogCommandType) Nothing
+    doesKnowCommandResolver = ValueResolver doesKnowCommandField
+        $ pure $ Boolean True
+    isHousetrainedField = Field Nothing (Out.NonNullScalarType boolean)
+        $ HashMap.singleton "atOtherHomes"
+        $ In.Argument Nothing (In.NamedScalarType boolean) Nothing
+    isHousetrainedResolver = ValueResolver isHousetrainedField
+        $ pure $ Boolean True
+    ownerField = Field Nothing (Out.NamedObjectType humanType) mempty
+    ownerResolver = ValueResolver ownerField $ pure Null
+
+dogDataType :: InputObjectType
+dogDataType = InputObjectType "DogData" Nothing
+    $ HashMap.singleton "name" nameInputField
+  where
+    nameInputField = InputField Nothing (In.NonNullScalarType string) Nothing
+
+sentientType :: InterfaceType IO
+sentientType = InterfaceType "Sentient" Nothing []
+    $ HashMap.singleton "name"
+    $ Field Nothing (Out.NonNullScalarType string) mempty
+
+petType :: InterfaceType IO
+petType = InterfaceType "Pet" Nothing []
+    $ HashMap.singleton "name"
+    $ Field Nothing (Out.NonNullScalarType string) mempty
+
+subscriptionType :: ObjectType IO
+subscriptionType = ObjectType "Subscription" Nothing [] $ HashMap.fromList
+    [ ("newMessage", newMessageResolver)
+    , ("disallowedSecondRootField", newMessageResolver)
+    ]
+  where
+    newMessageField = Field Nothing (Out.NonNullObjectType messageType) mempty
+    newMessageResolver = ValueResolver newMessageField
+        $ pure $ Object HashMap.empty
+
+messageType :: ObjectType IO
+messageType = ObjectType "Message" Nothing [] $ HashMap.fromList
+    [ ("sender", senderResolver)
+    , ("body", bodyResolver)
+    ]
+  where
+    senderField = Field Nothing (Out.NonNullScalarType string) mempty
+    senderResolver = ValueResolver senderField $ pure "Sender"
+    bodyField = Field Nothing (Out.NonNullScalarType string) mempty
+    bodyResolver = ValueResolver bodyField $ pure "Message body."
+
+humanType :: ObjectType IO
+humanType = ObjectType "Human" Nothing [sentientType] $ HashMap.fromList
+    [ ("name", nameResolver)
+    , ("pets", petsResolver)
+    ]
+  where
+    nameField = Field Nothing (Out.NonNullScalarType string) mempty
+    nameResolver = ValueResolver nameField $ pure "Name"
+    petsField =
+        Field Nothing (Out.ListType $ Out.NonNullInterfaceType petType) mempty
+    petsResolver = ValueResolver petsField $ pure $ List []
+{-
+catOrDogType :: UnionType IO
+catOrDogType = UnionType "CatOrDog" Nothing [catType, dogType]
+-}
+validate :: Text -> [Error]
+validate queryString =
+    case parse AST.document "" queryString of
+        Left _ -> []
+        Right ast -> toList $ document petSchema specifiedRules ast
+
+spec :: Spec
+spec =
+    describe "document" $ do
+        it "rejects type definitions" $
+            let queryString = [r|
+              query getDogName {
+                dog {
+                  name
+                  color
+                }
+              }
+
+              extend type Dog {
+                color: String
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Definition must be OperationDefinition or FragmentDefinition."
+                    , locations = [AST.Location 9 15]
+                    }
+               in validate queryString `shouldContain` [expected]
+
+        it "rejects multiple subscription root fields" $
+            let queryString = [r|
+              subscription sub {
+                newMessage {
+                  body
+                  sender
+                }
+                disallowedSecondRootField
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Subscription \"sub\" must select only one top level \
+                        \field."
+                    , locations = [AST.Location 2 15]
+                    }
+             in validate queryString `shouldContain` [expected]
+
+        it "rejects multiple subscription root fields coming from a fragment" $
+            let queryString = [r|
+              subscription sub {
+                ...multipleSubscriptions
+              }
+
+              fragment multipleSubscriptions on Subscription {
+                newMessage {
+                  body
+                  sender
+                }
+                disallowedSecondRootField
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Subscription \"sub\" must select only one top level \
+                        \field."
+                    , locations = [AST.Location 2 15]
+                    }
+             in validate queryString `shouldContain` [expected]
+
+        it "rejects multiple anonymous operations" $
+            let queryString = [r|
+              {
+                dog {
+                  name
+                }
+              }
+
+              query getName {
+                dog {
+                  owner {
+                    name
+                  }
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "This anonymous operation must be the only defined operation."
+                    , locations = [AST.Location 2 15]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects operations with the same name" $
+            let queryString = [r|
+              query dogOperation {
+                dog {
+                  name
+                }
+              }
+
+              mutation dogOperation {
+                mutateDog {
+                  id
+                }
+            }
+            |]
+                expected = Error
+                    { message =
+                        "There can be only one operation named \"dogOperation\"."
+                    , locations = [AST.Location 2 15, AST.Location 8 15]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects fragments with the same name" $
+            let queryString = [r|
+              {
+                dog {
+                  ...fragmentOne
+                }
+              }
+
+              fragment fragmentOne on Dog {
+                name
+              }
+
+              fragment fragmentOne on Dog {
+                owner {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "There can be only one fragment named \"fragmentOne\"."
+                    , locations = [AST.Location 8 15, AST.Location 12 15]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects the fragment spread without a target" $
+            let queryString = [r|
+              {
+                dog {
+                  ...undefinedFragment
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Fragment target \"undefinedFragment\" is undefined."
+                    , locations = [AST.Location 4 19]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects fragment spreads without an unknown target type" $
+            let queryString = [r|
+              {
+                dog {
+                  ...notOnExistingType
+                }
+              }
+              fragment notOnExistingType on NotInSchema {
+                name
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Fragment \"notOnExistingType\" is specified on type \
+                        \\"NotInSchema\" which doesn't exist in the schema."
+                    , locations = [AST.Location 4 19]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects inline fragments without a target" $
+            let queryString = [r|
+              {
+                ... on NotInSchema {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Inline fragment is specified on type \"NotInSchema\" \
+                        \which doesn't exist in the schema."
+                    , locations = [AST.Location 3 17]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects fragments on scalar types" $
+            let queryString = [r|
+              {
+                dog {
+                  ...fragOnScalar
+                }
+              }
+              fragment fragOnScalar on Int {
+                name
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Fragment cannot condition on non composite type \
+                        \\"Int\"."
+                    , locations = [AST.Location 7 15]
+                    }
+             in validate queryString `shouldContain` [expected]
+
+        it "rejects inline fragments on scalar types" $
+            let queryString = [r|
+              {
+                ... on Boolean {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Fragment cannot condition on non composite type \
+                        \\"Boolean\"."
+                    , locations = [AST.Location 3 17]
+                    }
+             in validate queryString `shouldContain` [expected]
+
+        it "rejects unused fragments" $
+            let queryString = [r|
+              fragment nameFragment on Dog { # unused
+                name
+              }
+
+              {
+                dog {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Fragment \"nameFragment\" is never used."
+                    , locations = [AST.Location 2 15]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects spreads that form cycles" $
+            let queryString = [r|
+              {
+                dog {
+                  ...nameFragment
+                }
+              }
+              fragment nameFragment on Dog {
+                name
+                ...barkVolumeFragment
+              }
+              fragment barkVolumeFragment on Dog {
+                barkVolume
+                ...nameFragment
+              }
+            |]
+                error1 = Error
+                    { message =
+                        "Cannot spread fragment \"barkVolumeFragment\" within \
+                        \itself (via barkVolumeFragment -> nameFragment -> \
+                        \barkVolumeFragment)."
+                    , locations = [AST.Location 11 15]
+                    }
+                error2 = Error
+                    { message =
+                        "Cannot spread fragment \"nameFragment\" within itself \
+                        \(via nameFragment -> barkVolumeFragment -> \
+                        \nameFragment)."
+                    , locations = [AST.Location 7 15]
+                    }
+             in validate queryString `shouldBe` [error1, error2]
+
+        it "rejects duplicate field arguments" $ do
+            let queryString = [r|
+              {
+                dog {
+                  isHousetrained(atOtherHomes: true, atOtherHomes: true)
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "There can be only one argument named \"atOtherHomes\"."
+                    , locations = [AST.Location 4 34, AST.Location 4 54]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects more than one directive per location" $ do
+            let queryString = [r|
+              query ($foo: Boolean = true, $bar: Boolean = false) {
+                dog @skip(if: $foo) @skip(if: $bar) {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "There can be only one directive named \"skip\"."
+                    , locations = [AST.Location 3 21, AST.Location 3 37]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects duplicate variables" $
+            let queryString = [r|
+              query houseTrainedQuery($atOtherHomes: Boolean, $atOtherHomes: Boolean) {
+                dog {
+                  isHousetrained(atOtherHomes: $atOtherHomes)
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "There can be only one variable named \"atOtherHomes\"."
+                    , locations = [AST.Location 2 39, AST.Location 2 63]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects non-input types as variables" $
+            let queryString = [r|
+              query takesDogBang($dog: Dog!) {
+                dog {
+                  isHousetrained(atOtherHomes: $dog)
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Variable \"$dog\" cannot be non-input type \"Dog\"."
+                    , locations = [AST.Location 2 34]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects undefined variables" $
+            let queryString = [r|
+              query variableIsNotDefinedUsedInSingleFragment {
+                dog {
+                  ...isHousetrainedFragment
+                }
+              }
+
+              fragment isHousetrainedFragment on Dog {
+                isHousetrained(atOtherHomes: $atOtherHomes)
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Variable \"$atOtherHomes\" is not defined by \
+                        \operation \
+                        \\"variableIsNotDefinedUsedInSingleFragment\"."
+                    , locations = [AST.Location 9 46]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects unused variables" $
+            let queryString = [r|
+              query variableUnused($atOtherHomes: Boolean) {
+                dog {
+                  isHousetrained
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Variable \"$atOtherHomes\" is never used in operation \
+                        \\"variableUnused\"."
+                    , locations = [AST.Location 2 36]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects duplicate fields in input objects" $
+            let queryString = [r|
+              {
+                findDog(complex: { name: "Fido", name: "Jack" }) {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "There can be only one input field named \"name\"."
+                    , locations = [AST.Location 3 36, AST.Location 3 50]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects undefined fields" $
+            let queryString = [r|
+              {
+                dog {
+                  meowVolume
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Cannot query field \"meowVolume\" on type \"Dog\"."
+                    , locations = [AST.Location 4 19]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects scalar fields with not empty selection set" $
+            let queryString = [r|
+              {
+                dog {
+                  barkVolume {
+                    sinceWhen
+                  }
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Field \"barkVolume\" must not have a selection since \
+                        \type \"Int\" has no subfields."
+                    , locations = [AST.Location 4 19]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects field arguments missing in the type" $
+            let queryString = [r|
+              {
+                dog {
+                  doesKnowCommand(command: CLEAN_UP_HOUSE, dogCommand: SIT)
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Unknown argument \"command\" on field \
+                        \\"Dog.doesKnowCommand\"."
+                    , locations = [AST.Location 4 35]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects directive arguments missing in the definition" $
+            let queryString = [r|
+              {
+                dog {
+                  isHousetrained(atOtherHomes: true) @include(unless: false, if: true)
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Unknown argument \"unless\" on directive \"@include\"."
+                    , locations = [AST.Location 4 63]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects undefined directives" $
+            let queryString = [r|
+              {
+                dog {
+                  isHousetrained(atOtherHomes: true) @ignore(if: true)
+                }
+              }
+            |]
+                expected = Error
+                    { message = "Unknown directive \"@ignore\"."
+                    , locations = [AST.Location 4 54]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects undefined input object fields" $
+            let queryString = [r|
+              {
+                findDog(complex: { favoriteCookieFlavor: "Bacon", name: "Jack" }) {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Field \"favoriteCookieFlavor\" is not defined \
+                        \by type \"DogData\"."
+                    , locations = [AST.Location 3 36]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects directives in invalid locations" $
+            let queryString = [r|
+              query @skip(if: $foo) {
+                dog {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message = "Directive \"@skip\" may not be used on QUERY."
+                    , locations = [AST.Location 2 21]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "rejects missing required input fields" $
+            let queryString = [r|
+              {
+                findDog(complex: { name: null }) {
+                  name
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Input field \"name\" of type \"DogData\" is required, \
+                        \but it was not provided."
+                    , locations = [AST.Location 3 34]
+                    }
+             in validate queryString `shouldBe` [expected]
+
+        it "finds corresponding subscription fragment" $
+            let queryString = [r|
+              subscription sub {
+                ...anotherSubscription
+                ...multipleSubscriptions
+              }
+              fragment multipleSubscriptions on Subscription {
+                newMessage {
+                  body
+                }
+                disallowedSecondRootField {
+                  sender
+                }
+              }
+              fragment anotherSubscription on Subscription {
+                newMessage {
+                  body
+                  sender
+                }
+              }
+            |]
+                expected = Error
+                    { message =
+                        "Subscription \"sub\" must select only one top level \
+                        \field."
+                    , locations = [AST.Location 2 15]
+                    }
+             in validate queryString `shouldBe` [expected]

tests/Test/DirectiveSpec.hs

@@ -1,88 +1,92 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE QuasiQuotes #-}
 module Test.DirectiveSpec
     ( spec
     ) where
 
-import Data.Aeson (Value, object, (.=))
-import Data.HashMap.Strict (HashMap)
+import Data.Aeson (object, (.=))
+import qualified Data.Aeson as Aeson
 import qualified Data.HashMap.Strict as HashMap
-import Data.List.NonEmpty (NonEmpty(..))
-import Data.Text (Text)
 import Language.GraphQL
-import qualified Language.GraphQL.Schema as Schema
-import Test.Hspec (Spec, describe, it, shouldBe)
+import Language.GraphQL.Type
+import qualified Language.GraphQL.Type.Out as Out
+import Test.Hspec (Spec, describe, it)
+import Test.Hspec.GraphQL
 import Text.RawString.QQ (r)
 
-experimentalResolver :: HashMap Text (NonEmpty (Schema.Resolver IO))
-experimentalResolver = HashMap.singleton "Query"
-    $ Schema.scalar "experimentalField" (pure (5 :: Int)) :| []
+experimentalResolver :: Schema IO
+experimentalResolver = schema queryType Nothing Nothing mempty
+  where
+    queryType = Out.ObjectType "Query" Nothing []
+        $ HashMap.singleton "experimentalField"
+        $ Out.ValueResolver (Out.Field Nothing (Out.NamedScalarType int) mempty)
+        $ pure $ Int 5
 
-emptyObject :: Value
-emptyObject = object
-    [ "data" .= object []
-    ]
+emptyObject :: Aeson.Object
+emptyObject = HashMap.singleton "data" $ object []
 
 spec :: Spec
 spec =
     describe "Directive executor" $ do
         it "should be able to @skip fields" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 experimentalField @skip(if: true)
               }
             |]
 
-            actual <- graphql experimentalResolver query
-            actual `shouldBe` emptyObject
+            actual <- graphql experimentalResolver sourceQuery
+            actual `shouldResolveTo` emptyObject
 
         it "should not skip fields if @skip is false" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 experimentalField @skip(if: false)
               }
             |]
-                expected = object
-                    [ "data" .= object
+                expected = HashMap.singleton "data"
+                    $ object
                         [ "experimentalField" .= (5 :: Int)
                         ]
-                    ]
-
-            actual <- graphql experimentalResolver query
-            actual `shouldBe` expected
+            actual <- graphql experimentalResolver sourceQuery
+            actual `shouldResolveTo` expected
 
         it "should skip fields if @include is false" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 experimentalField @include(if: false)
               }
             |]
 
-            actual <- graphql experimentalResolver query
-            actual `shouldBe` emptyObject
+            actual <- graphql experimentalResolver sourceQuery
+            actual `shouldResolveTo` emptyObject
 
         it "should be able to @skip a fragment spread" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 ...experimentalFragment @skip(if: true)
               }
 
-              fragment experimentalFragment on ExperimentalType {
+              fragment experimentalFragment on Query {
                 experimentalField
               }
             |]
 
-            actual <- graphql experimentalResolver query
-            actual `shouldBe` emptyObject
+            actual <- graphql experimentalResolver sourceQuery
+            actual `shouldResolveTo` emptyObject
 
         it "should be able to @skip an inline fragment" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
-                ... on ExperimentalType @skip(if: true) {
+                ... on Query @skip(if: true) {
                   experimentalField
                 }
               }
             |]
 
-            actual <- graphql experimentalResolver query
-            actual `shouldBe` emptyObject
+            actual <- graphql experimentalResolver sourceQuery
+            actual `shouldResolveTo` emptyObject

tests/Test/FragmentSpec.hs

@@ -1,35 +1,37 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE QuasiQuotes #-}
 module Test.FragmentSpec
     ( spec
     ) where
 
-import Data.Aeson (Value(..), object, (.=))
+import Data.Aeson ((.=))
+import qualified Data.Aeson as Aeson
 import qualified Data.HashMap.Strict as HashMap
-import Data.List.NonEmpty (NonEmpty(..))
 import Data.Text (Text)
 import Language.GraphQL
-import qualified Language.GraphQL.Schema as Schema
-import Test.Hspec ( Spec
-                  , describe
-                  , it
-                  , shouldBe
-                  , shouldSatisfy
-                  , shouldNotSatisfy
-                  )
+import Language.GraphQL.Type
+import qualified Language.GraphQL.Type.Out as Out
+import Test.Hspec (Spec, describe, it)
+import Test.Hspec.GraphQL
 import Text.RawString.QQ (r)
 
-size :: Schema.Resolver IO
-size = Schema.scalar "size" $ return ("L" :: Text)
+size :: (Text, Value)
+size = ("size", String "L")
 
-circumference :: Schema.Resolver IO
-circumference = Schema.scalar "circumference" $ return (60 :: Int)
+circumference :: (Text, Value)
+circumference = ("circumference", Int 60)
 
-garment :: Text -> Schema.Resolver IO
-garment typeName = Schema.object "garment" $ return
-    [ if typeName == "Hat" then circumference else size
-    , Schema.scalar "__typename" $ return typeName
-    ]
+garment :: Text -> (Text, Value)
+garment typeName =
+    ("garment",  Object $ HashMap.fromList
+        [ if typeName == "Hat" then circumference else size
+        , ("__typename", String typeName)
+        ]
+    )
 
 inlineQuery :: Text
 inlineQuery = [r|{
@@ -43,70 +45,92 @@ inlineQuery = [r|{
   }
 }|]
 
-hasErrors :: Value -> Bool
-hasErrors (Object object') = HashMap.member "errors" object'
-hasErrors _ = True
+shirtType :: Out.ObjectType IO
+shirtType = Out.ObjectType "Shirt" Nothing [] $ HashMap.fromList
+    [ ("size", sizeFieldType)
+    ]
+
+hatType :: Out.ObjectType IO
+hatType = Out.ObjectType "Hat" Nothing [] $ HashMap.fromList
+    [ ("size", sizeFieldType)
+    , ("circumference", circumferenceFieldType)
+    ]
+
+circumferenceFieldType :: Out.Resolver IO
+circumferenceFieldType
+    = Out.ValueResolver (Out.Field Nothing (Out.NamedScalarType int) mempty)
+    $ pure $ snd circumference
+
+sizeFieldType :: Out.Resolver IO
+sizeFieldType
+    = Out.ValueResolver (Out.Field Nothing (Out.NamedScalarType string) mempty)
+    $ pure $ snd size
+
+toSchema :: Text -> (Text, Value) -> Schema IO
+toSchema t (_, resolve) = schema queryType Nothing Nothing mempty
+  where
+    garmentType = Out.UnionType "Garment" Nothing [hatType, shirtType]
+    typeNameField = Out.Field Nothing (Out.NamedScalarType string) mempty
+    garmentField = Out.Field Nothing (Out.NamedUnionType garmentType) mempty
+    queryType =
+        case t of
+            "circumference" -> hatType
+            "size" -> shirtType
+            _ -> Out.ObjectType "Query" Nothing []
+                $ HashMap.fromList
+                    [ ("garment", ValueResolver garmentField (pure resolve))
+                    , ("__typename", ValueResolver typeNameField (pure $ String "Shirt"))
+                    ]
 
 spec :: Spec
 spec = do
     describe "Inline fragment executor" $ do
         it "chooses the first selection if the type matches" $ do
-            actual <- graphql (HashMap.singleton "Query" $ garment "Hat" :| []) inlineQuery
-            let expected = object
-                    [ "data" .= object
-                        [ "garment" .= object
+            actual <- graphql (toSchema "Hat" $ garment "Hat") inlineQuery
+            let expected = HashMap.singleton "data"
+                    $ Aeson.object
+                        [ "garment" .= Aeson.object
                             [ "circumference" .= (60 :: Int)
                             ]
                         ]
-                    ]
-             in actual `shouldBe` expected
+             in actual `shouldResolveTo` expected
 
         it "chooses the last selection if the type matches" $ do
-            actual <- graphql (HashMap.singleton "Query" $ garment "Shirt" :| []) inlineQuery
-            let expected = object
-                    [ "data" .= object
-                        [ "garment" .= object
+            actual <- graphql (toSchema "Shirt" $ garment "Shirt") inlineQuery
+            let expected = HashMap.singleton "data"
+                    $ Aeson.object
+                        [ "garment" .= Aeson.object
                             [ "size" .= ("L" :: Text)
                             ]
                         ]
-                    ]
-             in actual `shouldBe` expected
+             in actual `shouldResolveTo` expected
 
         it "embeds inline fragments without type" $ do
-            let query = [r|{
-              garment {
-                circumference
-                ... {
-                  size
-                }
-              }
-            }|]
-                resolvers = Schema.object "garment" $ return [circumference,  size]
-
-            actual <- graphql (HashMap.singleton "Query" $ resolvers :| []) query
-            let expected = object
-                    [ "data" .= object
-                        [ "garment" .= object
-                            [ "circumference" .= (60 :: Int)
-                            , "size" .= ("L" :: Text)
-                            ]
-                        ]
-                    ]
-             in actual `shouldBe` expected
-
-        it "evaluates fragments on Query" $ do
-            let query = [r|{
+            let sourceQuery = [r|{
+              circumference
               ... {
                 size
               }
             }|]
+            actual <- graphql (toSchema "circumference" circumference) sourceQuery
+            let expected = HashMap.singleton "data"
+                    $ Aeson.object
+                        [ "circumference" .= (60 :: Int)
+                        , "size" .= ("L" :: Text)
+                        ]
+             in actual `shouldResolveTo` expected
 
-            actual <- graphql (HashMap.singleton "Query" $ size :| []) query
-            actual `shouldNotSatisfy` hasErrors
+        it "evaluates fragments on Query" $ do
+            let sourceQuery = [r|{
+              ... {
+                size
+              }
+            }|]
+             in graphql (toSchema "size" size) `shouldResolve` sourceQuery
 
     describe "Fragment spread executor" $ do
         it "evaluates fragment spreads" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 ...circumferenceFragment
               }
@@ -116,16 +140,15 @@ spec = do
               }
             |]
 
-            actual <- graphql (HashMap.singleton "Query" $ circumference :| []) query
-            let expected = object
-                    [ "data" .= object
+            actual <- graphql (toSchema "circumference" circumference) sourceQuery
+            let expected = HashMap.singleton "data"
+                    $ Aeson.object
                         [ "circumference" .= (60 :: Int)
                         ]
-                    ]
-             in actual `shouldBe` expected
+             in actual `shouldResolveTo` expected
 
         it "evaluates nested fragments" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 garment {
                   ...circumferenceFragment
@@ -141,32 +164,17 @@ spec = do
               }
             |]
 
-            actual <- graphql (HashMap.singleton "Query" $ garment "Hat" :| []) query
-            let expected = object
-                    [ "data" .= object
-                        [ "garment" .= object
+            actual <- graphql (toSchema "Hat" $ garment "Hat") sourceQuery
+            let expected = HashMap.singleton "data"
+                    $ Aeson.object
+                        [ "garment" .= Aeson.object
                             [ "circumference" .= (60 :: Int)
                             ]
                         ]
-                    ]
-             in actual `shouldBe` expected
-
-        it "rejects recursive fragments" $ do
-            let query = [r|
-              {
-                ...circumferenceFragment
-              }
-
-              fragment circumferenceFragment on Hat {
-                ...circumferenceFragment
-              }
-            |]
-
-            actual <- graphql (HashMap.singleton "Query" $ circumference :| []) query
-            actual `shouldSatisfy` hasErrors
+             in actual `shouldResolveTo` expected
 
         it "considers type condition" $ do
-            let query = [r|
+            let sourceQuery = [r|
               {
                 garment {
                   ...circumferenceFragment
@@ -180,12 +188,11 @@ spec = do
                 size
               }
             |]
-                expected = object
-                    [ "data" .= object
-                        [ "garment" .= object
+                expected = HashMap.singleton "data"
+                    $ Aeson.object
+                        [ "garment" .= Aeson.object
                             [ "circumference" .= (60 :: Int)
                             ]
                         ]
-                    ]
-            actual <- graphql (HashMap.singleton "Query" $ garment "Hat" :| []) query
-            actual `shouldBe` expected
+            actual <- graphql (toSchema "Hat" $ garment "Hat") sourceQuery
+            actual `shouldResolveTo` expected

tests/Test/KitchenSinkSpec.hs

@@ -1,69 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE QuasiQuotes #-}
-module Test.KitchenSinkSpec
-    ( spec
-    ) where
-
-import qualified Data.Text.IO as Text.IO
-import qualified Data.Text.Lazy.IO as Text.Lazy.IO
-import qualified Data.Text.Lazy as Lazy (Text)
-import qualified Language.GraphQL.AST.Encoder as Encoder
-import qualified Language.GraphQL.AST.Parser as Parser
-import Paths_graphql (getDataFileName)
-import Test.Hspec (Spec, describe, it)
-import Test.Hspec.Megaparsec (parseSatisfies)
-import Text.Megaparsec (parse)
-import Text.RawString.QQ (r)
-
-spec :: Spec
-spec = describe "Kitchen Sink" $ do
-    it "minifies the query" $ do
-        dataFileName <- getDataFileName "tests/data/kitchen-sink.graphql"
-        minFileName <- getDataFileName "tests/data/kitchen-sink.min.graphql"
-        expected <- Text.Lazy.IO.readFile minFileName
-
-        shouldNormalize Encoder.minified dataFileName expected
-
-    it "pretty prints the query" $ do
-        dataFileName <- getDataFileName "tests/data/kitchen-sink.graphql"
-        let expected = [r|query queryName($foo: ComplexType, $site: Site = MOBILE) {
-  whoever123is: node(id: [123, 456]) {
-    id
-    ... on User @defer {
-      field2 {
-        id
-        alias: field1(first: 10, after: $foo) @include(if: $foo) {
-          id
-          ...frag
-        }
-      }
-    }
-  }
-}
-
-mutation likeStory {
-  like(story: 123) @defer {
-    story {
-      id
-    }
-  }
-}
-
-fragment frag on Friend {
-  foo(size: $size, bar: $b, obj: {key: "value"})
-}
-
-{
-  unnamed(truthy: true, falsey: false)
-  query
-}
-|]
-
-        shouldNormalize Encoder.pretty dataFileName expected
-
-shouldNormalize :: Encoder.Formatter -> FilePath -> Lazy.Text -> IO ()
-shouldNormalize formatter dataFileName expected = do
-    actual <- Text.IO.readFile dataFileName
-    parse Parser.document dataFileName actual `parseSatisfies` condition
-      where
-        condition = (expected ==) . Encoder.document formatter

tests/Test/RootOperationSpec.hs

@@ -0,0 +1,72 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+module Test.RootOperationSpec
+    ( spec
+    ) where
+
+import Data.Aeson ((.=), object)
+import qualified Data.HashMap.Strict as HashMap
+import Language.GraphQL
+import Test.Hspec (Spec, describe, it)
+import Text.RawString.QQ (r)
+import Language.GraphQL.Type
+import qualified Language.GraphQL.Type.Out as Out
+import Test.Hspec.GraphQL
+
+hatType :: Out.ObjectType IO
+hatType = Out.ObjectType "Hat" Nothing []
+    $ HashMap.singleton "circumference"
+    $ ValueResolver (Out.Field Nothing (Out.NamedScalarType int) mempty)
+    $ pure $ Int 60
+
+garmentSchema :: Schema IO
+garmentSchema = schema queryType (Just mutationType) Nothing mempty
+  where
+    queryType = Out.ObjectType "Query" Nothing [] hatFieldResolver
+    mutationType = Out.ObjectType "Mutation" Nothing [] incrementFieldResolver
+    garment = pure $ Object $ HashMap.fromList
+        [ ("circumference", Int 60)
+        ]
+    incrementFieldResolver = HashMap.singleton "incrementCircumference"
+        $ ValueResolver (Out.Field Nothing (Out.NamedScalarType int) mempty)
+        $ pure $ Int 61
+    hatField = Out.Field Nothing (Out.NamedObjectType hatType) mempty
+    hatFieldResolver =
+        HashMap.singleton "garment" $ ValueResolver hatField garment
+
+spec :: Spec
+spec =
+    describe "Root operation type" $ do
+        it "returns objects from the root resolvers" $ do
+            let querySource = [r|
+              {
+                garment {
+                  circumference
+                }
+              }
+            |]
+                expected = HashMap.singleton "data"
+                    $ object
+                        [ "garment" .= object
+                            [ "circumference" .= (60 :: Int)
+                            ]
+                        ]
+            actual <- graphql garmentSchema querySource
+            actual `shouldResolveTo` expected
+
+        it "chooses Mutation" $ do
+            let querySource = [r|
+              mutation {
+                incrementCircumference
+              }
+            |]
+                expected = HashMap.singleton "data"
+                    $ object
+                        [ "incrementCircumference" .= (61 :: Int)
+                        ]
+            actual <- graphql garmentSchema querySource
+            actual `shouldResolveTo` expected

tests/Test/StarWars/Data.hs

@@ -1,191 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-module Test.StarWars.Data
-    ( Character
-    , appearsIn
-    , artoo
-    , getDroid
-    , getDroid'
-    , getEpisode
-    , getFriends
-    , getHero
-    , getHuman
-    , id_
-    , homePlanet
-    , name
-    , secretBackstory
-    , typeName
-    ) where
-
-import Data.Functor.Identity (Identity)
-import Control.Applicative (Alternative(..), liftA2)
-import Control.Monad.Trans.Except (throwE)
-import Data.Maybe (catMaybes)
-import Data.Text (Text)
-import Language.GraphQL.Trans
-import qualified Language.GraphQL.Type as Type
-
--- * Data
--- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsData.js
-
--- ** Characters
-
-type ID = Text
-
-data CharCommon = CharCommon
-  { _id_        :: ID
-  , _name       :: Text
-  , _friends    :: [ID]
-  , _appearsIn  :: [Int]
-  } deriving (Show)
-
-
-data Human = Human
-  { _humanChar  :: CharCommon
-  , homePlanet :: Text
-  }
-
-data Droid = Droid
-  { _droidChar       :: CharCommon
-  , primaryFunction :: Text
-  }
-
-type Character = Either Droid Human
-
-id_ :: Character -> ID
-id_ (Left  x) = _id_ . _droidChar $ x
-id_ (Right x) = _id_ . _humanChar $ x
-
-name :: Character -> Text
-name (Left  x) = _name . _droidChar $ x
-name (Right x) = _name . _humanChar $ x
-
-friends :: Character -> [ID]
-friends (Left  x) = _friends . _droidChar $ x
-friends (Right x) = _friends . _humanChar $ x
-
-appearsIn :: Character -> [Int]
-appearsIn (Left  x) = _appearsIn . _droidChar $ x
-appearsIn (Right x) = _appearsIn . _humanChar $ x
-
-secretBackstory :: Character -> ActionT Identity Text
-secretBackstory = const $ ActionT $ throwE "secretBackstory is secret."
-
-typeName :: Character -> Text
-typeName = either (const "Droid") (const "Human")
-
-luke :: Character
-luke = Right luke'
-
-luke' :: Human
-luke' = Human
-  { _humanChar = CharCommon
-      { _id_        = "1000"
-      , _name       = "Luke Skywalker"
-      , _friends    = ["1002","1003","2000","2001"]
-      , _appearsIn  = [4,5,6]
-      }
-  , homePlanet = "Tatooine"
-  }
-
-vader :: Human
-vader = Human
-  { _humanChar = CharCommon
-      { _id_        = "1001"
-      , _name       = "Darth Vader"
-      , _friends    = ["1004"]
-      , _appearsIn  = [4,5,6]
-      }
-  , homePlanet = "Tatooine"
-  }
-
-han :: Human
-han = Human
-  { _humanChar = CharCommon
-      { _id_        = "1002"
-      , _name       = "Han Solo"
-      , _friends    = ["1000","1003","2001" ]
-      , _appearsIn  = [4,5,6]
-      }
-  , homePlanet = mempty
-  }
-
-leia :: Human
-leia = Human
-  { _humanChar = CharCommon
-      { _id_        = "1003"
-      , _name       = "Leia Organa"
-      , _friends    = ["1000","1002","2000","2001"]
-      , _appearsIn  = [4,5,6]
-      }
-  , homePlanet = "Alderaan"
-  }
-
-tarkin :: Human
-tarkin = Human
-  { _humanChar = CharCommon
-    { _id_        = "1004"
-    , _name       = "Wilhuff Tarkin"
-    , _friends    = ["1001"]
-    , _appearsIn  = [4]
-    }
-  , homePlanet = mempty
-  }
-
-threepio :: Droid
-threepio = Droid
-  { _droidChar = CharCommon
-      { _id_ = "2000"
-      , _name = "C-3PO"
-      , _friends = ["1000","1002","1003","2001" ]
-      , _appearsIn = [ 4, 5, 6 ]
-      }
-  , primaryFunction = "Protocol"
-  }
-
-artoo :: Character
-artoo = Left artoo'
-
-artoo' :: Droid
-artoo' = Droid
-  { _droidChar = CharCommon
-      { _id_        = "2001"
-      , _name       = "R2-D2"
-      , _friends    = ["1000","1002","1003"]
-      , _appearsIn  = [4,5,6]
-      }
-  , primaryFunction = "Astrometch"
-  }
-
--- ** Helper functions
-
-getHero :: Int -> Character
-getHero 5 = luke
-getHero _ = artoo
-
-getHuman :: Alternative f => ID -> f Character
-getHuman = fmap Right . getHuman'
-
-getHuman' :: Alternative f => ID -> f Human
-getHuman' "1000" = pure luke'
-getHuman' "1001" = pure vader
-getHuman' "1002" = pure han
-getHuman' "1003" = pure leia
-getHuman' "1004" = pure tarkin
-getHuman' _      = empty
-
-getDroid :: Alternative f => ID -> f Character
-getDroid = fmap Left . getDroid'
-
-getDroid' :: Alternative f => ID -> f Droid
-getDroid' "2000" = pure threepio
-getDroid' "2001" = pure artoo'
-getDroid' _      = empty
-
-getFriends :: Character -> [Character]
-getFriends char = catMaybes $ liftA2 (<|>) getDroid getHuman <$> friends char
-
-getEpisode :: Int -> Maybe (Type.Wrapping Text)
-getEpisode 4 = pure $ Type.Named "NEWHOPE"
-getEpisode 5 = pure $ Type.Named "EMPIRE"
-getEpisode 6 = pure $ Type.Named "JEDI"
-getEpisode _ = empty

tests/Test/StarWars/QuerySpec.hs

@@ -1,365 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE QuasiQuotes #-}
-module Test.StarWars.QuerySpec
-    ( spec
-    ) where
-
-import qualified Data.Aeson as Aeson
-import Data.Aeson ((.=))
-import Data.Functor.Identity (Identity(..))
-import qualified Data.HashMap.Strict as HashMap
-import Data.Text (Text)
-import Language.GraphQL
-import Language.GraphQL.Schema (Subs)
-import Text.RawString.QQ (r)
-import Test.Hspec.Expectations (Expectation, shouldBe)
-import Test.Hspec (Spec, describe, it)
-import Test.StarWars.Schema
-
--- * Test
--- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsQueryTests.js
-
-spec :: Spec
-spec = describe "Star Wars Query Tests" $ do
-    describe "Basic Queries" $ do
-      it "R2-D2 hero" $ testQuery
-        [r| query HeroNameQuery {
-            hero {
-                id
-            }
-            }
-        |]
-        $ Aeson.object
-            [ "data" .= Aeson.object
-                [ "hero" .= Aeson.object ["id" .= ("2001" :: Text)]
-                ]
-            ]
-      it "R2-D2 ID and friends" $ testQuery
-        [r| query HeroNameAndFriendsQuery {
-            hero {
-                id
-                name
-                friends {
-                name
-                }
-            }
-            }
-        |]
-        $ Aeson.object [ "data" .= Aeson.object [
-            "hero" .= Aeson.object
-                [ "id" .= ("2001" :: Text)
-                , r2d2Name
-                , "friends" .=
-                    [ Aeson.object [lukeName]
-                    , Aeson.object [hanName]
-                    , Aeson.object [leiaName]
-                    ]
-                ]
-        ]]
-
-    describe "Nested Queries" $ do
-      it "R2-D2 friends" $ testQuery
-        [r| query NestedQuery {
-              hero {
-                name
-                friends {
-                  name
-                  appearsIn
-                    friends {
-                      name
-                    }
-                }
-              }
-            }
-        |]
-        $ Aeson.object [ "data" .= Aeson.object [
-          "hero" .= Aeson.object [
-              "name" .= ("R2-D2" :: Text)
-            , "friends" .= [
-                  Aeson.object [
-                      "name" .= ("Luke Skywalker" :: Text)
-                    , "appearsIn" .= ["NEWHOPE","EMPIRE","JEDI" :: Text]
-                    , "friends" .= [
-                          Aeson.object [hanName]
-                        , Aeson.object [leiaName]
-                        , Aeson.object [c3poName]
-                        , Aeson.object [r2d2Name]
-                        ]
-                    ]
-                , Aeson.object [
-                      hanName
-                    , "appearsIn" .= [ "NEWHOPE","EMPIRE","JEDI" :: Text]
-                    , "friends" .=
-                        [ Aeson.object [lukeName]
-                        , Aeson.object [leiaName]
-                        , Aeson.object [r2d2Name]
-                        ]
-                    ]
-                , Aeson.object [
-                      leiaName
-                    , "appearsIn" .= [ "NEWHOPE","EMPIRE","JEDI" :: Text]
-                    , "friends" .=
-                        [ Aeson.object [lukeName]
-                        , Aeson.object [hanName]
-                        , Aeson.object [c3poName]
-                        , Aeson.object [r2d2Name]
-                        ]
-                    ]
-                ]
-            ]
-        ]]
-      it "Luke ID" $ testQuery
-        [r| query FetchLukeQuery {
-              human(id: "1000") {
-                name
-              }
-            }
-        |]
-        $ Aeson.object [ "data" .= Aeson.object
-            [ "human" .= Aeson.object [lukeName]
-            ]]
-
-    it "Luke ID with variable" $ testQueryParams
-      (HashMap.singleton "someId" "1000")
-      [r| query FetchSomeIDQuery($someId: String!) {
-            human(id: $someId) {
-              name
-            }
-          }
-      |]
-      $ Aeson.object [ "data" .= Aeson.object [
-        "human" .= Aeson.object [lukeName]
-      ]]
-    it "Han ID with variable" $ testQueryParams
-      (HashMap.singleton "someId" "1002")
-      [r| query FetchSomeIDQuery($someId: String!) {
-            human(id: $someId) {
-              name
-            }
-          }
-      |]
-      $ Aeson.object [ "data" .= Aeson.object [
-        "human" .= Aeson.object [hanName]
-      ]]
-    it "Invalid ID" $ testQueryParams
-      (HashMap.singleton "id" "Not a valid ID")
-      [r| query humanQuery($id: String!) {
-            human(id: $id) {
-              name
-            }
-          }
-      |] $ Aeson.object ["data" .= Aeson.object ["human" .= Aeson.Null]]
-    it "Luke aliased" $ testQuery
-      [r| query FetchLukeAliased {
-            luke: human(id: "1000") {
-              name
-            }
-          }
-      |]
-      $ Aeson.object [ "data" .= Aeson.object [
-       "luke" .= Aeson.object [lukeName]
-      ]]
-    it "R2-D2 ID and friends aliased" $ testQuery
-      [r| query HeroNameAndFriendsQuery {
-            hero {
-              id
-              name
-              friends {
-                friendName: name
-              }
-            }
-          }
-      |]
-      $ Aeson.object [ "data" .= Aeson.object [
-        "hero" .= Aeson.object [
-            "id" .= ("2001" :: Text)
-          , r2d2Name
-          , "friends" .=
-              [ Aeson.object ["friendName" .= ("Luke Skywalker" :: Text)]
-              , Aeson.object ["friendName" .= ("Han Solo" :: Text)]
-              , Aeson.object ["friendName" .= ("Leia Organa" :: Text)]
-              ]
-          ]
-      ]]
-    it "Luke and Leia aliased" $ testQuery
-      [r| query FetchLukeAndLeiaAliased {
-            luke: human(id: "1000") {
-              name
-            }
-            leia: human(id: "1003") {
-              name
-            }
-          }
-      |]
-      $ Aeson.object [ "data" .= Aeson.object
-        [ "luke" .= Aeson.object [lukeName]
-        , "leia" .= Aeson.object [leiaName]
-      ]]
-
-    describe "Fragments for complex queries" $ do
-      it "Aliases to query for duplicate content" $ testQuery
-        [r| query DuplicateFields {
-              luke: human(id: "1000") {
-                name
-                homePlanet
-              }
-              leia: human(id: "1003") {
-                name
-                homePlanet
-              }
-            }
-        |]
-        $ Aeson.object [ "data" .= Aeson.object [
-          "luke" .= Aeson.object [lukeName, tatooine]
-        , "leia" .= Aeson.object [leiaName, alderaan]
-        ]]
-      it "Fragment for duplicate content" $ testQuery
-        [r|  query UseFragment {
-              luke: human(id: "1000") {
-                ...HumanFragment
-              }
-              leia: human(id: "1003") {
-                ...HumanFragment
-              }
-            }
-            fragment HumanFragment on Human {
-              name
-              homePlanet
-            }
-        |]
-        $ Aeson.object [ "data" .= Aeson.object [
-          "luke" .= Aeson.object [lukeName, tatooine]
-        , "leia" .= Aeson.object [leiaName, alderaan]
-        ]]
-
-    describe "__typename" $ do
-      it "R2D2 is a Droid" $ testQuery
-        [r| query CheckTypeOfR2 {
-              hero {
-                __typename
-                name
-              }
-            }
-          |]
-        $ Aeson.object ["data" .= Aeson.object [
-            "hero" .= Aeson.object
-                [ "__typename" .= ("Droid" :: Text)
-                , r2d2Name
-                ]
-        ]]
-      it "Luke is a human" $ testQuery
-        [r| query CheckTypeOfLuke {
-              hero(episode: EMPIRE) {
-                __typename
-                name
-              }
-            }
-          |]
-        $ Aeson.object ["data" .= Aeson.object [
-            "hero" .= Aeson.object
-                [ "__typename" .= ("Human" :: Text)
-                , lukeName
-                ]
-        ]]
-
-    describe "Errors in resolvers" $ do
-        it "error on secretBackstory" $ testQuery
-          [r|
-            query HeroNameQuery {
-              hero {
-                name
-                  secretBackstory
-              }
-            }
-          |]
-          $ Aeson.object
-              [ "data" .= Aeson.object
-                  [ "hero" .= Aeson.object
-                      [ "name" .= ("R2-D2" :: Text)
-                      , "secretBackstory" .= Aeson.Null
-                      ]
-                  ]
-              , "errors" .=
-                  [ Aeson.object
-                      ["message" .= ("secretBackstory is secret." :: Text)]
-                  ]
-              ]
-        it "Error in a list" $ testQuery
-          [r| query HeroNameQuery {
-                hero {
-                  name
-                  friends {
-                    name
-                    secretBackstory
-                  }
-                }
-              }
-            |]
-          $ Aeson.object ["data" .= Aeson.object
-            [ "hero" .= Aeson.object
-                [ "name" .= ("R2-D2" :: Text)
-                , "friends" .=
-                    [ Aeson.object
-                        [ "name" .= ("Luke Skywalker" :: Text)
-                        , "secretBackstory" .= Aeson.Null
-                        ]
-                    , Aeson.object
-                        [ "name" .= ("Han Solo" :: Text)
-                        , "secretBackstory" .= Aeson.Null
-                        ]
-                    , Aeson.object
-                        [ "name" .= ("Leia Organa" :: Text)
-                        , "secretBackstory" .= Aeson.Null
-                        ]
-                    ]
-                ]
-            ]
-            , "errors" .=
-                [ Aeson.object
-                    [ "message" .= ("secretBackstory is secret." :: Text)
-                    ]
-                , Aeson.object
-                    [ "message" .= ("secretBackstory is secret." :: Text)
-                    ]
-                , Aeson.object
-                    [ "message" .= ("secretBackstory is secret." :: Text)
-                    ]
-                ]
-            ]
-        it "error on secretBackstory with alias" $ testQuery
-          [r| query HeroNameQuery {
-                mainHero: hero {
-                  name
-                  story: secretBackstory
-                }
-              }
-            |]
-          $ Aeson.object
-              [ "data" .= Aeson.object
-                  [ "mainHero" .= Aeson.object
-                      [ "name" .= ("R2-D2" :: Text)
-                      , "story" .= Aeson.Null
-                      ]
-                  ]
-              , "errors" .=
-                  [ Aeson.object
-                    [ "message" .= ("secretBackstory is secret." :: Text)
-                    ]
-                  ]
-              ]
-
-  where
-    lukeName = "name" .= ("Luke Skywalker" :: Text)
-    leiaName = "name" .= ("Leia Organa" :: Text)
-    hanName = "name" .= ("Han Solo" :: Text)
-    r2d2Name = "name" .= ("R2-D2" :: Text)
-    c3poName = "name" .= ("C-3PO" :: Text)
-    tatooine = "homePlanet" .= ("Tatooine" :: Text)
-    alderaan = "homePlanet" .= ("Alderaan" :: Text)
-
-testQuery :: Text -> Aeson.Value -> Expectation
-testQuery q expected = runIdentity (graphql schema q) `shouldBe` expected
-
-testQueryParams :: Subs -> Text -> Aeson.Value -> Expectation
-testQueryParams f q expected =
-    runIdentity (graphqlSubs schema f q) `shouldBe` expected

tests/Test/StarWars/Schema.hs

@@ -1,66 +0,0 @@
-{-# LANGUAGE OverloadedStrings #-}
-module Test.StarWars.Schema
-    ( character
-    , droid
-    , hero
-    , human
-    , schema
-    ) where
-
-import Control.Monad.Trans.Except (throwE)
-import Control.Monad.Trans.Class (lift)
-import Data.Functor.Identity (Identity)
-import Data.HashMap.Strict (HashMap)
-import qualified Data.HashMap.Strict as HashMap
-import Data.List.NonEmpty (NonEmpty(..))
-import Data.Maybe (catMaybes)
-import Data.Text (Text)
-import qualified Language.GraphQL.Schema as Schema
-import Language.GraphQL.Trans
-import qualified Language.GraphQL.Type as Type
-import Test.StarWars.Data
-
--- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsSchema.js
-
-schema :: HashMap Text (NonEmpty (Schema.Resolver Identity))
-schema = HashMap.singleton "Query" $ hero :| [human, droid]
-
-hero :: Schema.Resolver Identity
-hero = Schema.object "hero" $ do
-  episode <- argument "episode"
-  character $ case episode of
-      Schema.Enum "NEWHOPE" -> getHero 4
-      Schema.Enum "EMPIRE" -> getHero 5
-      Schema.Enum "JEDI" -> getHero 6
-      _ -> artoo
-
-human :: Schema.Resolver Identity
-human = Schema.wrappedObject "human" $ do
-    id' <- argument "id"
-    case id' of
-        Schema.String i -> do
-            humanCharacter <- lift $ return $ getHuman i >>= Just
-            case humanCharacter of
-                Nothing -> return Type.Null
-                Just e -> Type.Named <$> character e
-        _ -> ActionT $ throwE "Invalid arguments."
-
-droid :: Schema.Resolver Identity
-droid = Schema.object "droid" $ do
-    id' <- argument "id"
-    case id' of
-        Schema.String i -> character =<< getDroid i
-        _ -> ActionT $ throwE "Invalid arguments."
-
-character :: Character -> ActionT Identity [Schema.Resolver Identity]
-character char = return
-    [ Schema.scalar "id" $ return $ id_ char
-    , Schema.scalar "name" $ return $ name char
-    , Schema.wrappedObject "friends"
-        $ traverse character $ Type.List $ Type.Named <$> getFriends char
-    , Schema.wrappedScalar "appearsIn" $ return . Type.List
-        $ catMaybes (getEpisode <$> appearsIn char)
-    , Schema.scalar "secretBackstory" $ secretBackstory char
-    , Schema.scalar "homePlanet" $ return $ either mempty homePlanet char
-    , Schema.scalar "__typename" $ return $ typeName char
-    ]

tests/data/kitchen-sink.graphql

@@ -1,38 +0,0 @@
-# Copyright (c) 2015, Facebook, Inc.
-# All rights reserved.
-#
-# This source code is licensed under the BSD-style license found in the
-# LICENSE file in the root directory of this source tree. An additional grant
-# of patent rights can be found in the PATENTS file in the same directory.
-
-query queryName($foo: ComplexType, $site: Site = MOBILE) {
-  whoever123is: node(id: [123, 456]) {
-    id, # Inline test comment
-    ... on User @defer {
-      field2 {
-        id,
-        alias: field1(first: 10, after: $foo) @include(if: $foo) {
-          id,
-          ...frag
-        }
-      }
-    }
-  }
-}
-
-mutation likeStory {
-  like(story: 123) @defer {
-    story {
-      id
-    }
-  }
-}
-
-fragment frag on Friend {
-  foo(size: $size, bar: $b, obj: {key: "value"})
-}
-
-{
-  unnamed(truthy: true, falsey: false),
-  query
-}

tests/data/kitchen-sink.min.graphql

@@ -1 +0,0 @@
-query queryName($foo:ComplexType,$site:Site=MOBILE){whoever123is:node(id:[123,456]){id,... on User@defer{field2{id,alias:field1(first:10,after:$foo)@include(if:$foo){id,...frag}}}}}mutation likeStory{like(story:123)@defer{story{id}}}fragment frag on Friend{foo(size:$size,bar:$b,obj:{key:"value"})}{unnamed(truthy:true,falsey:false),query}