Release 1.2.0.2

inside an input object for the role checking for unused and undefined
variables.

.gitea/workflows/build.yml

@@ -0,0 +1,68 @@
+name: Build
+
+on:
+  push:
+  pull_request:
+    branches: [master]
+
+jobs:
+  audit:
+    runs-on: alpine
+    steps:
+      - name: Set up environment
+        shell: ash {0}
+        run: |
+          apk add --no-cache git bash curl build-base readline-dev openssl-dev zlib-dev libpq-dev gmp-dev
+      - name: Prepare system
+        run: |
+          curl --create-dirs --output-dir \
+            ~/.ghcup/bin https://downloads.haskell.org/~ghcup/0.1.19.5/x86_64-linux-ghcup-0.1.19.5 -o ghcup
+          chmod +x ~/.ghcup/bin/ghcup
+          ~/.ghcup/bin/ghcup install ghc 9.4.8
+          ~/.ghcup/bin/ghcup install cabal 3.6.2.0
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: |
+          ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal update
+          ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal install hlint --constraint="hlint ==3.6.1"
+      - run: ~/.cabal/bin/hlint -- src tests
+
+  test:
+    runs-on: alpine
+    steps:
+      - name: Set up environment
+        shell: ash {0}
+        run: |
+          apk add --no-cache git bash curl build-base readline-dev openssl-dev zlib-dev libpq-dev gmp-dev
+      - name: Prepare system
+        run: |
+          curl --create-dirs --output-dir \
+            ~/.ghcup/bin https://downloads.haskell.org/~ghcup/0.1.19.5/x86_64-linux-ghcup-0.1.19.5 -o ghcup
+          chmod +x ~/.ghcup/bin/ghcup
+          ~/.ghcup/bin/ghcup install ghc 9.4.8
+          ~/.ghcup/bin/ghcup install cabal 3.6.2.0
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: |
+          ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal update
+          ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal build graphql-test
+      - run: ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal test --test-show-details=direct
+
+  doc:
+    runs-on: alpine
+    steps:
+      - name: Set up environment
+        shell: ash {0}
+        run: |
+          apk add --no-cache git bash curl build-base readline-dev openssl-dev zlib-dev libpq-dev gmp-dev
+      - name: Prepare system
+        run: |
+          curl --create-dirs --output-dir \
+            ~/.ghcup/bin https://downloads.haskell.org/~ghcup/0.1.19.5/x86_64-linux-ghcup-0.1.19.5 -o ghcup
+          chmod +x ~/.ghcup/bin/ghcup
+          ~/.ghcup/bin/ghcup install ghc 9.4.8
+          ~/.ghcup/bin/ghcup install cabal 3.6.2.0
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal update
+      - run: ~/.ghcup/bin/ghcup run --ghc 9.4.8 --cabal 3.6.2.0 -- cabal haddock --enable-documentation

CHANGELOG.md

@@ -6,6 +6,56 @@ The format is based on
 and this project adheres to
 [Haskell Package Versioning Policy](https://pvp.haskell.org/).
 
+## [1.2.0.2] - 2024-01-09
+### Fixed
+- `gql` removes not only leading `\n` but also `\r`.
+- Fix non nullable type string representation in executor error messages.
+- Fix input objects not being coerced to lists.
+- Fix used variables are not found in the properties of input objects.
+
+## [1.2.0.1] - 2023-04-25
+### Fixed
+- Support hspec 2.11.
+
+## [1.2.0.0] - 2023-02-28
+### Added
+- Schema printing.
+- `Semigroup` and `Monoid` instances for `AST.Document.Description`.
+- Support for vector 0.13.0.0 and transformers 0.6.1.0.
+
+### Fixed
+- Fix resolvers returning a list in the reverse order.
+
+### Removed
+- GHC 8 support.
+- Cabal -json flag.
+- `Test.Hspec.GraphQL`: moved to `graphql-spice` package.
+- CPP `ifdef WITH_JSON` blocks.
+
+## [1.1.0.0] - 2022-12-24
+### Changed
+- Removed deprecated `Language.GraphQL.Error` functions: `addErr`, `addErrMsg`,
+  `singleError`.
+- Deprecate `Resolution`, `CollectErrsT` and `runCollectErrs` in the `Error`
+  module. It was already noted in the documentation that these symbols are
+  deprecated, now a pragma is added.
+- `Language.GraphQL`: Added information about the *json* flag and switching to
+  *graphql-spice* for JSON support.
+
+### Added
+- Partial schema printing: operation type encoder.
+
+## [1.0.3.0] - 2022-03-27
+### Fixed
+- Index position in error path. (Index and Segment paths of a field have been
+  swapped).
+- Parsing empty list as an argument.
+
+### Added
+- quickCheck Parser test for arguments. Arbitrary instances for Language.GraphQL.AST.Document.
+- Enhanced query error messages. Add tests for these cases.
+- Allow version 2.0 of the text package.
+
 ## [1.0.2.0] - 2021-12-26
 ### Added
 - `Serialize` instance for `Type.Definition.Value`.
@@ -361,7 +411,6 @@ and this project adheres to
 - `Language.GraphQL.Schema`: `enum`, `enumA`, `wrappedEnum` and `wrappedEnumA`.
   Use `scalar`, `scalarA`, `wrappedScalar` and `wrappedScalarA` instead.
 
-
 ## [0.5.1.0] - 2019-10-22
 ### Deprecated
 - `Language.GraphQL.AST.Arguments`. Use `[Language.GraphQL.AST.Argument]`
@@ -466,21 +515,26 @@ and this project adheres to
 ### Added
 - Data types for the GraphQL language.
 
-[1.0.2.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=1.0.2.0&rev_to=v1.0.1.0
+[1.2.0.2]: https://git.caraus.tech/OSS/graphql/compare/v1.2.0.1...v1.2.0.2
-[1.0.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v1.0.1.0&rev_to=v1.0.0.0
+[1.2.0.1]: https://git.caraus.tech/OSS/graphql/compare/v1.2.0.0...v1.2.0.1
-[1.0.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v1.0.0.0&rev_to=v0.11.1.0
+[1.2.0.0]: https://git.caraus.tech/OSS/graphql/compare/v1.1.0.0...v1.2.0.0
-[0.11.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.11.1.0&rev_to=v0.11.0.0
+[1.1.0.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.3.0...v1.1.0.0
-[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
+[1.0.3.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.2.0...v1.0.3.0
-[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
+[1.0.2.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.1.0...v1.0.2.0
-[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
+[1.0.1.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.0.0...v1.0.1.0
-[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
+[1.0.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.11.1.0...v1.0.0.0
-[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
+[0.11.1.0]: https://git.caraus.tech/OSS/graphql/compare/v0.11.0.0...v0.11.1.0
-[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
+[0.11.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.10.0.0...v0.11.0.0
-[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
+[0.10.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.9.0.0...v0.10.0.0
-[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
+[0.9.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.8.0.0...v0.9.0.0
-[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
+[0.8.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.7.0.0...v0.8.0.0
-[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
+[0.7.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.6.1.0...v0.7.0.0
-[0.4.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.4.0.0&rev_to=v0.3
+[0.6.1.0]: https://git.caraus.tech/OSS/graphql/compare/v0.6.0.0...v0.6.1.0
-[0.3]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.3&rev_to=v0.2.1
+[0.6.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.5.1.0...v0.6.0.0
-[0.2.1]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.2.1&rev_to=v0.2
+[0.5.1.0]: https://git.caraus.tech/OSS/graphql/compare/v0.5.0.1...v0.5.1.0
-[0.2]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.2&rev_to=v0.1
+[0.5.0.1]: https://git.caraus.tech/OSS/graphql/compare/v0.5.0.0...v0.5.0.1
+[0.5.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.4.0.0...v0.5.0.0
+[0.4.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.3...v0.4.0.0
+[0.3]: https://git.caraus.tech/OSS/graphql/compare/v0.2.1...v0.3
+[0.2.1]: https://git.caraus.tech/OSS/graphql/compare/v0.2...v0.2.1
+[0.2]: https://git.caraus.tech/OSS/graphql/compare/v0.1...v0.2

README.md

@@ -1,15 +1,12 @@
 # GraphQL implementation in Haskell
 
-[![Simple Haskell](https://www.simplehaskell.org/badges/badge.svg)](https://www.simplehaskell.org)
+See https://git.caraus.tech/OSS/graphql.
-[![CI/CD](https://img.shields.io/badge/CI-CD-brightgreen)](https://build.caraus.tech/go/pipelines)
-
-See https://www.caraus.tech/projects/pub-graphql.
 
 Report issues on the
-[bug tracker](https://www.caraus.tech/projects/pub-graphql/issues).
+[bug tracker](https://git.caraus.tech/OSS/graphql/issues).
 
 API documentation is available through
 [Hackage](https://hackage.haskell.org/package/graphql).
 
 Further documentation will be made available in the
-[Wiki](https://www.caraus.tech/projects/pub-graphql/wiki).
+[Wiki](https://git.caraus.tech/OSS/graphql/wiki).

graphql.cabal

@@ -1,17 +1,17 @@
 cabal-version: 2.4
 
 name:           graphql
-version:        1.0.2.0
+version:        1.2.0.2
 synopsis:       Haskell GraphQL implementation
 description:    Haskell <https://spec.graphql.org/June2018/ GraphQL> implementation.
 category:       Language
-homepage:       https://www.caraus.tech/projects/pub-graphql
+homepage:       https://git.caraus.tech/OSS/graphql
-bug-reports:    https://www.caraus.tech/projects/pub-graphql/issues
+bug-reports:    https://git.caraus.tech/OSS/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) 2019-2021 Eugen Wissner,
+copyright:      (c) 2019-2024 Eugen Wissner,
                 (c) 2015-2017 J. Daniel Navarro
 license:        MPL-2.0 AND BSD-3-Clause
 license-files:  LICENSE,
@@ -21,18 +21,12 @@ extra-source-files:
   CHANGELOG.md
   README.md
 tested-with:
-  GHC == 8.10.7,
+  GHC == 9.4.7,
-  GHC == 9.0.1,
+  GHC == 9.6.3
-  GHC == 9.2.1
 
 source-repository head
   type: git
-  location: git://caraus.tech/pub/graphql.git
+  location: https://git.caraus.tech/OSS/graphql.git
-
-flag Json
-  description: Whether to build against @aeson 1.x@
-  default: True
-  manual: True
 
 library
   exposed-modules:
@@ -54,7 +48,6 @@ library
     Language.GraphQL.Type.Schema
     Language.GraphQL.Validate
     Language.GraphQL.Validate.Validation
-    Test.Hspec.GraphQL
   other-modules:
     Language.GraphQL.Execute.Transform
     Language.GraphQL.Type.Definition
@@ -72,16 +65,10 @@ library
     megaparsec >= 9.0 && < 10,
     parser-combinators >= 1.3 && < 2,
     template-haskell >= 2.16 && < 3,
-    text ^>= 1.2.4,
+    text >= 1.2 && < 3,
-    transformers ^>= 0.5.6,
+    transformers >= 0.5.6 && < 0.7,
     unordered-containers ^>= 0.2.14,
-    vector ^>= 0.12.3
+    vector >= 0.12 && < 0.14
-  if flag(Json)
-    build-depends:
-      aeson >= 1.5.6 && < 1.6,
-      hspec-expectations >= 0.8.2 && < 0.9,
-      scientific >= 0.3.7 && < 0.4
-    cpp-options: -DWITH_JSON
 
   default-language: Haskell2010
 
@@ -93,12 +80,14 @@ test-suite graphql-test
     Language.GraphQL.AST.EncoderSpec
     Language.GraphQL.AST.LexerSpec
     Language.GraphQL.AST.ParserSpec
+    Language.GraphQL.AST.Arbitrary
     Language.GraphQL.ErrorSpec
     Language.GraphQL.Execute.CoerceSpec
     Language.GraphQL.Execute.OrderedMapSpec
     Language.GraphQL.ExecuteSpec
     Language.GraphQL.Type.OutSpec
     Language.GraphQL.Validate.RulesSpec
+    Schemas.HeroSchema
   hs-source-dirs:
     tests
   ghc-options: -threaded -rtsopts -with-rtsopts=-N -Wall
@@ -109,9 +98,14 @@ test-suite graphql-test
     conduit,
     exceptions,
     graphql,
-    hspec ^>= 2.9.1,
+    hspec >= 2.10.9 && < 2.12,
+    hspec-expectations ^>= 0.8.2,
     hspec-megaparsec ^>= 2.2.0,
     megaparsec,
     text,
-    unordered-containers
+    unordered-containers,
+    containers,
+    vector
+  build-tool-depends:
+    hspec-discover:hspec-discover
   default-language: Haskell2010

src/Language/GraphQL.hs

@@ -1,84 +1,46 @@
-{-# LANGUAGE CPP #-}
-
-#ifdef WITH_JSON
-{-# 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.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 qualified Data.Text as Text
+import qualified Language.GraphQL.AST as Full
 import Language.GraphQL.Error
 import Language.GraphQL.Execute
 import qualified Language.GraphQL.Validate as Validate
 import Language.GraphQL.Type.Schema (Schema)
+import Prelude hiding (null)
 import Text.Megaparsec (parse)
 
 -- | If the text parses correctly as a @GraphQL@ query the query is
 -- executed using the given 'Schema'.
-graphql :: MonadCatch m
+--
-    => Schema m -- ^ Resolvers.
+-- An operation name can be given if the document contains multiple operations.
-    -> Text -- ^ Text representing a @GraphQL@ request document.
+graphql :: (MonadCatch m, VariableValue a, Serialize b)
-    -> 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'.
-graphqlSubs :: MonadCatch m
     => Schema m -- ^ Resolvers.
     -> Maybe Text -- ^ Operation name.
-    -> Aeson.Object -- ^ Variable substitution function.
+    -> HashMap Full.Name a -- ^ Variable substitution function.
     -> Text -- ^ Text representing a @GraphQL@ request document.
-    -> m (Either (ResponseEventStream m Aeson.Value) Aeson.Object) -- ^ Response.
+    -> m (Either (ResponseEventStream m b) (Response b)) -- ^ Response.
-graphqlSubs schema operationName variableValues document' =
+graphql schema operationName variableValues document' =
-    case parse document "" document' of
+    case parse Full.document "" document' of
-        Left errorBundle -> pure . formatResponse <$> parseError errorBundle
+        Left errorBundle -> pure  <$> parseError errorBundle
         Right parsed ->
             case validate parsed of
-                Seq.Empty -> fmap formatResponse
+                Seq.Empty -> execute schema operationName variableValues parsed
-                    <$> execute schema operationName variableValues parsed
                 errors -> pure $ pure
-                    $ HashMap.singleton "errors"
+                    $ Response null
-                    $ Aeson.toJSON
                     $ fromValidationError <$> errors
   where
     validate = Validate.document schema Validate.specifiedRules
-    formatResponse (Response data'' Seq.Empty) = HashMap.singleton "data" data''
+    fromValidationError Validate.Error{..} = Error
-    formatResponse (Response data'' errors') = HashMap.fromList
+        { message = Text.pack message
-        [ ("data", data'')
+        , locations = locations
-        , ("errors", Aeson.toJSON $ fromError <$> errors')
+        , path = []
-        ]
+        }
-    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)
-        ]
-#else
--- | This module provides the functions to parse and execute @GraphQL@ queries.
-module Language.GraphQL
-    (
-    ) where
-#endif

src/Language/GraphQL/AST/Document.hs

@@ -49,6 +49,8 @@ module Language.GraphQL.AST.Document
     , Value(..)
     , VariableDefinition(..)
     , escape
+    , showVariableName
+    , showVariable
     ) where
 
 import Data.Char (ord)
@@ -339,6 +341,12 @@ data VariableDefinition =
     VariableDefinition Name Type (Maybe (Node ConstValue)) Location
     deriving (Eq, Show)
 
+showVariableName :: VariableDefinition -> String
+showVariableName (VariableDefinition name _ _ _) = "$" <> Text.unpack name
+
+showVariable :: VariableDefinition -> String
+showVariable var@(VariableDefinition _ type' _ _) = showVariableName var <> ":" <> " " <> show type'
+
 -- ** Type References
 
 -- | Type representation.
@@ -363,8 +371,8 @@ data NonNullType
     deriving Eq
 
 instance Show NonNullType where
-    show (NonNullTypeNamed typeName) = '!' : Text.unpack typeName
+    show (NonNullTypeNamed typeName) = Text.unpack $ typeName <> "!"
-    show (NonNullTypeList listType) =  concat ["![", show listType, "]"]
+    show (NonNullTypeList listType) = concat ["[", show listType, "]!"]
 
 -- ** Directives
 
@@ -456,6 +464,14 @@ data SchemaExtension
 newtype Description = Description (Maybe Text)
     deriving (Eq, Show)
 
+instance Semigroup Description
+  where
+    Description lhs <> Description rhs = Description $ lhs <> rhs
+
+instance Monoid Description
+  where
+    mempty = Description mempty
+
 -- ** Types
 
 -- | Type definitions describe various user-defined types.

src/Language/GraphQL/AST/Encoder.hs

@@ -11,12 +11,14 @@ module Language.GraphQL.AST.Encoder
     , directive
     , document
     , minified
+    , operationType
     , pretty
     , type'
+    , typeSystemDefinition
     , value
     ) where
 
-import Data.Foldable (fold)
+import Data.Foldable (fold, Foldable (..))
 import qualified Data.List.NonEmpty as NonEmpty
 import Data.Text (Text)
 import qualified Data.Text as Text
@@ -27,6 +29,7 @@ import qualified Data.Text.Lazy.Builder as Builder
 import Data.Text.Lazy.Builder.Int (decimal)
 import Data.Text.Lazy.Builder.RealFloat (realFloat)
 import qualified Language.GraphQL.AST.Document as Full
+import qualified Language.GraphQL.AST.DirectiveLocation as DirectiveLocation
 
 -- | Instructs the encoder whether the GraphQL document should be minified or
 --   pretty printed.
@@ -34,7 +37,7 @@ import qualified Language.GraphQL.AST.Document as Full
 --   Use 'pretty' or 'minified' to construct the formatter.
 data Formatter
     = Minified
-    | Pretty Word
+    | Pretty !Word
 
 -- | Constructs a formatter for pretty printing.
 pretty :: Formatter
@@ -53,7 +56,246 @@ document formatter defs
     encodeDocument = foldr executableDefinition [] defs
     executableDefinition (Full.ExecutableDefinition executableDefinition') acc =
         definition formatter executableDefinition' : acc
-    executableDefinition _ acc = acc
+    executableDefinition (Full.TypeSystemDefinition typeSystemDefinition' _location) acc =
+        typeSystemDefinition formatter typeSystemDefinition' : acc
+    executableDefinition (Full.TypeSystemExtension typeSystemExtension' _location) acc =
+        typeSystemExtension formatter typeSystemExtension' : acc
+
+directiveLocation :: DirectiveLocation.DirectiveLocation -> Lazy.Text
+directiveLocation = Lazy.Text.pack . show
+
+withLineBreak :: Formatter -> Lazy.Text.Text -> Lazy.Text.Text
+withLineBreak formatter encodeDefinition
+    | Pretty _ <- formatter = Lazy.Text.snoc encodeDefinition '\n'
+    | Minified <- formatter = encodeDefinition
+
+typeSystemExtension :: Formatter -> Full.TypeSystemExtension -> Lazy.Text
+typeSystemExtension formatter = \case
+    Full.SchemaExtension schemaExtension' ->
+        schemaExtension formatter schemaExtension'
+    Full.TypeExtension typeExtension' -> typeExtension formatter typeExtension'
+
+schemaExtension :: Formatter -> Full.SchemaExtension -> Lazy.Text
+schemaExtension formatter = \case
+    Full.SchemaOperationExtension operationDirectives operationTypeDefinitions' ->
+        withLineBreak formatter
+            $ "extend schema "
+            <> optempty (directives formatter) operationDirectives
+            <> bracesList formatter (operationTypeDefinition formatter) (NonEmpty.toList operationTypeDefinitions')
+    Full.SchemaDirectivesExtension operationDirectives -> "extend schema "
+        <> optempty (directives formatter) (NonEmpty.toList operationDirectives)
+
+typeExtension :: Formatter -> Full.TypeExtension -> Lazy.Text
+typeExtension formatter = \case
+    Full.ScalarTypeExtension name' directives'
+        -> "extend scalar "
+        <> Lazy.Text.fromStrict name'
+        <> directives formatter (NonEmpty.toList directives')
+    Full.ObjectTypeFieldsDefinitionExtension name' ifaces' directives' fields'
+        -> "extend type "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (" " <>) (implementsInterfaces ifaces')
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (fieldDefinition nextFormatter) (NonEmpty.toList fields')
+    Full.ObjectTypeDirectivesExtension name' ifaces' directives'
+        -> "extend type "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (" " <>) (implementsInterfaces ifaces')
+        <> optempty (directives formatter) (NonEmpty.toList directives')
+    Full.ObjectTypeImplementsInterfacesExtension name' ifaces'
+        -> "extend type "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (" " <>) (implementsInterfaces ifaces')
+    Full.InterfaceTypeFieldsDefinitionExtension name' directives' fields'
+        -> "extend interface "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (fieldDefinition nextFormatter) (NonEmpty.toList fields')
+    Full.InterfaceTypeDirectivesExtension name' directives'
+        -> "extend interface "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) (NonEmpty.toList directives')
+    Full.UnionTypeUnionMemberTypesExtension name' directives' members'
+        -> "extend union "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> unionMemberTypes formatter members'
+    Full.UnionTypeDirectivesExtension name' directives'
+        -> "extend union "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) (NonEmpty.toList directives')
+    Full.EnumTypeEnumValuesDefinitionExtension name' directives' members'
+        -> "extend enum "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (enumValueDefinition formatter) (NonEmpty.toList members')
+    Full.EnumTypeDirectivesExtension name' directives'
+        -> "extend enum "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) (NonEmpty.toList directives')
+    Full.InputObjectTypeInputFieldsDefinitionExtension name' directives' fields'
+        -> "extend input "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (inputValueDefinition nextFormatter) (NonEmpty.toList fields')
+    Full.InputObjectTypeDirectivesExtension name' directives'
+        -> "extend input "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) (NonEmpty.toList directives')
+  where
+    nextFormatter = incrementIndent formatter
+
+-- | Converts a t'Full.TypeSystemDefinition' into a string.
+typeSystemDefinition :: Formatter -> Full.TypeSystemDefinition -> Lazy.Text
+typeSystemDefinition formatter = \case
+    Full.SchemaDefinition operationDirectives operationTypeDefinitions' ->
+        withLineBreak formatter
+            $ "schema "
+            <> optempty (directives formatter) operationDirectives
+            <> bracesList formatter (operationTypeDefinition formatter) (NonEmpty.toList operationTypeDefinitions')
+    Full.TypeDefinition typeDefinition' -> typeDefinition formatter typeDefinition'
+    Full.DirectiveDefinition description' name' arguments' locations
+        -> description formatter description'
+        <> "@"
+        <> Lazy.Text.fromStrict name'
+        <> argumentsDefinition formatter arguments'
+        <> " on"
+        <> pipeList formatter (directiveLocation <$> locations)
+
+operationTypeDefinition :: Formatter -> Full.OperationTypeDefinition -> Lazy.Text.Text
+operationTypeDefinition formatter (Full.OperationTypeDefinition operationType' namedType')
+    = indentLine (incrementIndent formatter)
+    <> operationType formatter operationType'
+    <> colon formatter
+    <> Lazy.Text.fromStrict namedType'
+
+fieldDefinition :: Formatter -> Full.FieldDefinition -> Lazy.Text.Text
+fieldDefinition formatter fieldDefinition' =
+    let Full.FieldDefinition description' name' arguments' type'' directives' = fieldDefinition'
+     in optempty (description formatter) description'
+            <> indentLine formatter
+            <> Lazy.Text.fromStrict name'
+            <> argumentsDefinition formatter arguments'
+            <> colon formatter
+            <> type' type''
+            <> optempty (directives formatter) directives'
+
+argumentsDefinition :: Formatter -> Full.ArgumentsDefinition -> Lazy.Text.Text
+argumentsDefinition formatter (Full.ArgumentsDefinition arguments') =
+    parensCommas formatter (argumentDefinition formatter) arguments'
+
+argumentDefinition :: Formatter -> Full.InputValueDefinition -> Lazy.Text.Text
+argumentDefinition formatter definition' =
+    let Full.InputValueDefinition description' name' type'' defaultValue' directives' = definition'
+     in optempty (description formatter) description'
+            <> Lazy.Text.fromStrict name'
+            <> colon formatter
+            <> type' type''
+            <> maybe mempty (defaultValue formatter . Full.node) defaultValue'
+            <> directives formatter directives'
+
+inputValueDefinition :: Formatter -> Full.InputValueDefinition -> Lazy.Text.Text
+inputValueDefinition formatter definition' =
+    let Full.InputValueDefinition description' name' type'' defaultValue' directives' = definition'
+     in optempty (description formatter) description'
+            <> indentLine formatter
+            <> Lazy.Text.fromStrict name'
+            <> colon formatter
+            <> type' type''
+            <> maybe mempty (defaultValue formatter . Full.node) defaultValue'
+            <> directives formatter directives'
+
+typeDefinition :: Formatter -> Full.TypeDefinition -> Lazy.Text
+typeDefinition formatter = \case
+    Full.ScalarTypeDefinition description' name' directives'
+        -> optempty (description formatter) description'
+        <> "scalar "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+    Full.ObjectTypeDefinition description' name' ifaces' directives' fields'
+        -> optempty (description formatter) description'
+        <> "type "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (" " <>) (implementsInterfaces ifaces')
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (fieldDefinition nextFormatter) fields'
+    Full.InterfaceTypeDefinition description' name' directives' fields'
+        -> optempty (description formatter) description'
+        <> "interface "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (fieldDefinition nextFormatter) fields'
+    Full.UnionTypeDefinition description' name' directives' members'
+        -> optempty (description formatter) description'
+        <> "union "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> unionMemberTypes formatter members'
+    Full.EnumTypeDefinition description' name' directives' members'
+        -> optempty (description formatter) description'
+        <> "enum "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (enumValueDefinition formatter) members'
+    Full.InputObjectTypeDefinition description' name' directives' fields'
+        -> optempty (description formatter) description'
+        <> "input "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+        <> eitherFormat formatter " " ""
+        <> bracesList formatter (inputValueDefinition nextFormatter) fields'
+  where
+    nextFormatter = incrementIndent formatter
+
+implementsInterfaces :: Foldable t => Full.ImplementsInterfaces t -> Lazy.Text
+implementsInterfaces (Full.ImplementsInterfaces interfaces)
+    | null interfaces = mempty
+    | otherwise = Lazy.Text.fromStrict
+        $ Text.append "implements "
+        $ Text.intercalate " & "
+        $ toList interfaces
+
+unionMemberTypes :: Foldable t => Formatter -> Full.UnionMemberTypes t -> Lazy.Text
+unionMemberTypes formatter (Full.UnionMemberTypes memberTypes)
+    | null memberTypes = mempty
+    | otherwise = Lazy.Text.append "="
+        $ pipeList formatter
+        $ Lazy.Text.fromStrict
+        <$> toList memberTypes
+
+pipeList :: Foldable t => Formatter -> t Lazy.Text -> Lazy.Text
+pipeList Minified =  (" " <>) . Lazy.Text.intercalate " | " . toList
+pipeList (Pretty _) =  Lazy.Text.concat
+    . fmap (("\n" <> indentSymbol <> "| ") <>)
+    . toList 
+
+enumValueDefinition :: Formatter -> Full.EnumValueDefinition -> Lazy.Text
+enumValueDefinition (Pretty _) enumValue =
+    let Full.EnumValueDefinition description' name' directives' = enumValue
+        formatter = Pretty 1
+     in description formatter description'
+        <> indentLine formatter
+        <> Lazy.Text.fromStrict name'
+        <> directives formatter directives'
+enumValueDefinition Minified enumValue =
+    let Full.EnumValueDefinition description' name' directives' = enumValue
+     in description Minified description'
+        <> Lazy.Text.fromStrict name'
+        <> directives Minified directives'
+
+description :: Formatter -> Full.Description -> Lazy.Text.Text
+description _formatter (Full.Description Nothing) = ""
+description formatter (Full.Description (Just description')) =
+    stringValue formatter description'
 
 -- | Converts a t'Full.ExecutableDefinition' into a string.
 definition :: Formatter -> Full.ExecutableDefinition -> Lazy.Text
@@ -99,9 +341,9 @@ variableDefinition formatter variableDefinition' =
     let Full.VariableDefinition variableName variableType defaultValue' _ =
             variableDefinition'
      in variable variableName
-    <> eitherFormat formatter ": " ":"
+    <> colon formatter
     <> type' variableType
-    <> maybe mempty (defaultValue formatter) (Full.node <$> defaultValue')
+    <> maybe mempty (defaultValue formatter . Full.node) defaultValue'
 
 defaultValue :: Formatter -> Full.ConstValue -> Lazy.Text
 defaultValue formatter val
@@ -126,20 +368,26 @@ indent :: (Integral a) => a -> Lazy.Text
 indent indentation = Lazy.Text.replicate (fromIntegral indentation) indentSymbol
 
 selection :: Formatter -> Full.Selection -> Lazy.Text
-selection formatter = Lazy.Text.append indent' . encodeSelection
+selection formatter = Lazy.Text.append (indentLine formatter')
+    . encodeSelection
   where
     encodeSelection (Full.FieldSelection fieldSelection) =
-        field incrementIndent fieldSelection
+        field formatter' fieldSelection
     encodeSelection (Full.InlineFragmentSelection fragmentSelection) =
-        inlineFragment incrementIndent fragmentSelection
+        inlineFragment formatter' fragmentSelection
     encodeSelection (Full.FragmentSpreadSelection fragmentSelection) =
-        fragmentSpread incrementIndent fragmentSelection
+        fragmentSpread formatter' fragmentSelection
-    incrementIndent
+    formatter' = incrementIndent formatter
+
+indentLine :: Formatter -> Lazy.Text
+indentLine formatter
+    | Pretty indentation <- formatter = indent indentation
+    | otherwise = ""
+
+incrementIndent :: Formatter -> Formatter
+incrementIndent formatter
     | Pretty indentation <- formatter = Pretty $ indentation + 1
     | otherwise = Minified
-    indent'
-        | Pretty indentation <- formatter = indent $ indentation + 1
-        | otherwise = ""
 
 colon :: Formatter -> Lazy.Text
 colon formatter = eitherFormat formatter ": " ":"
@@ -197,8 +445,10 @@ directive formatter (Full.Directive name args _)
     = "@" <> Lazy.Text.fromStrict name <> optempty (arguments formatter) args
 
 directives :: Formatter -> [Full.Directive] -> Lazy.Text
-directives Minified = spaces (directive Minified)
+directives Minified values = spaces (directive Minified) values
-directives formatter = Lazy.Text.cons ' ' . spaces (directive formatter)
+directives formatter values
+    | null values = ""
+    | otherwise = Lazy.Text.cons ' ' $ spaces (directive formatter) values
 
 -- | Converts a 'Full.Value' into a string.
 value :: Formatter -> Full.Value -> Lazy.Text
@@ -294,6 +544,12 @@ nonNullType :: Full.NonNullType -> Lazy.Text
 nonNullType (Full.NonNullTypeNamed x) = Lazy.Text.fromStrict x <> "!"
 nonNullType (Full.NonNullTypeList x) = listType x <> "!"
 
+-- | Produces lowercase operation type: query, mutation or subscription.
+operationType :: Formatter -> Full.OperationType -> Lazy.Text
+operationType _formatter Full.Query = "query"
+operationType _formatter Full.Mutation = "mutation"
+operationType _formatter Full.Subscription = "subscription"
+
 -- * Internal
 
 between :: Char -> Char -> Lazy.Text -> Lazy.Text

src/Language/GraphQL/AST/Lexer.hs

@@ -58,6 +58,7 @@ import qualified Text.Megaparsec.Char.Lexer as Lexer
 import Data.Text (Text)
 import qualified Data.Text as T
 import qualified Data.Text.Lazy as TL
+import Control.Monad (void)
 
 -- | Standard parser.
 -- Accepts the type of the parsed token.
@@ -93,7 +94,7 @@ dollar = symbol "$"
 
 -- | Parser for "@".
 at :: Parser ()
-at = symbol "@" >> pure ()
+at = void $ symbol "@"
 
 -- | Parser for "&".
 amp :: Parser T.Text
@@ -101,7 +102,7 @@ amp = symbol "&"
 
 -- | Parser for ":".
 colon :: Parser ()
-colon = symbol ":" >> pure ()
+colon = void $ symbol ":"
 
 -- | Parser for "=".
 equals :: Parser T.Text
@@ -220,7 +221,7 @@ escapeSequence = do
 
 -- | Parser for the "Byte Order Mark".
 unicodeBOM :: Parser ()
-unicodeBOM = optional (char '\xfeff') >> pure ()
+unicodeBOM = void $ optional $ char '\xfeff'
 
 -- | Parses "extend" followed by a 'symbol'. It is used by schema extensions.
 extend :: forall a. Text -> String -> NonEmpty (Parser a) -> Parser a

src/Language/GraphQL/AST/Parser.hs

@@ -450,8 +450,8 @@ value = Full.Variable <$> variable
     <|> Full.Null <$  nullValue
     <|> Full.String <$> stringValue
     <|> Full.Enum <$> try enumValue
-    <|> Full.List <$> brackets (some $ valueNode value)
+    <|> Full.List <$> brackets (many $ valueNode value)
-    <|> Full.Object <$> braces (some $ objectField $ valueNode value)
+    <|> Full.Object <$> braces (many $ objectField $ valueNode value)
     <?> "Value"
 
 constValue :: Parser Full.ConstValue

src/Language/GraphQL/Error.hs

@@ -15,16 +15,13 @@ module Language.GraphQL.Error
     , ResolverException(..)
     , Response(..)
     , ResponseEventStream
-    , addErr
-    , addErrMsg
     , parseError
     , runCollectErrs
-    , singleError
     ) where
 
 import Conduit
 import Control.Exception (Exception(..))
-import Control.Monad.Trans.State (StateT, modify, runStateT)
+import Control.Monad.Trans.State (StateT, runStateT)
 import Data.HashMap.Strict (HashMap)
 import Data.Sequence (Seq(..), (|>))
 import qualified Data.Sequence as Seq
@@ -103,11 +100,9 @@ instance Exception ResolverException
 
 -- * Deprecated
 
+{-# DEPRECATED runCollectErrs "runCollectErrs was part of the old executor and isn't used anymore" #-}
 -- | Runs the given query computation, but collects the errors into an error
 -- list, which is then sent back with the data.
---
--- /runCollectErrs was part of the old executor and isn't used anymore, it will
--- be deprecated in the future and removed./
 runCollectErrs :: (Monad m, Serialize a)
     => HashMap Name (Schema.Type m)
     -> CollectErrsT m a
@@ -117,40 +112,13 @@ runCollectErrs types' res = do
         $ Resolution{ errors = Seq.empty, types = types' }
     pure $ Response dat errors
 
+{-# DEPRECATED Resolution "Resolution was part of the old executor and isn't used anymore" #-}
 -- | Executor context.
---
--- /Resolution was part of the old executor and isn't used anymore, it will be
--- deprecated in the future and removed./
 data Resolution m = Resolution
     { errors :: Seq Error
     , types :: HashMap Name (Schema.Type m)
     }
 
+{-# DEPRECATED CollectErrsT "CollectErrsT was part of the old executor and isn't used anymore" #-}
 -- | A wrapper to pass error messages around.
---
--- /CollectErrsT was part of the old executor and isn't used anymore, it will be
--- deprecated in the future and removed./
 type CollectErrsT m = StateT (Resolution m) m
-
--- | Adds an error to the list of errors.
-{-# DEPRECATED #-}
-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 }
-
-{-# DEPRECATED #-}
-makeErrorMessage :: Text -> Error
-makeErrorMessage s = Error s [] []
-
--- | Constructs a response object containing only the error with the given
--- message.
-{-# DEPRECATED #-}
-singleError :: Serialize a => Text -> Response a
-singleError message = Response null $ Seq.singleton $ Error message [] []
-
--- | Convenience function for just wrapping an error message.
-{-# DEPRECATED #-}
-addErrMsg :: (Monad m, Serialize a) => Text -> CollectErrsT m a
-addErrMsg errorMessage = (addErr . makeErrorMessage) errorMessage >> pure null

src/Language/GraphQL/Execute.hs

@@ -39,6 +39,7 @@ import qualified Data.List.NonEmpty as NonEmpty
 import Data.Maybe (fromMaybe)
 import Data.Sequence (Seq)
 import qualified Data.Sequence as Seq
+import qualified Data.Vector as Vector
 import Data.Text (Text)
 import qualified Data.Text as Text
 import Data.Typeable (cast)
@@ -61,6 +62,7 @@ import Language.GraphQL.Error
     , ResponseEventStream
     )
 import Prelude hiding (null)
+import Language.GraphQL.AST.Document (showVariableName)
 
 newtype ExecutorT m a = ExecutorT
     { runExecutorT :: ReaderT (HashMap Full.Name (Type m)) (WriterT (Seq Error) m) a
@@ -190,32 +192,42 @@ data QueryError
 tell :: Monad m => Seq Error -> ExecutorT m ()
 tell = ExecutorT . lift . Writer.tell
 
+operationNameErrorText :: Text
+operationNameErrorText = Text.unlines
+    [ "Named operations must be provided with the name of the desired operation."
+    , "See https://spec.graphql.org/June2018/#sec-Language.Document description."
+    ]
+
 queryError :: QueryError -> Error
 queryError OperationNameRequired =
-    Error{ message = "Operation name is required.", locations = [], path = [] }
+    let queryErrorMessage = "Operation name is required. " <> operationNameErrorText
+    in Error{ message = queryErrorMessage, locations = [], path = [] }
 queryError (OperationNotFound operationName) =
-    let queryErrorMessage = Text.concat
+    let queryErrorMessage = Text.unlines
+            [ Text.concat
               [ "Operation \""
               , Text.pack operationName
-            , "\" not found."
+              , "\" is not found in the named operations you've provided. "
+              ]
+            , operationNameErrorText
             ]
      in Error{ message = queryErrorMessage, locations = [], path = [] }
 queryError (CoercionError variableDefinition) =
-    let Full.VariableDefinition variableName _ _ location = variableDefinition
+    let (Full.VariableDefinition _ _ _ location) = variableDefinition
         queryErrorMessage = Text.concat
-            [ "Failed to coerce the variable \""
+            [ "Failed to coerce the variable "
-            , variableName
+            , Text.pack $ Full.showVariable variableDefinition
-            , "\"."
+            , "."
             ]
      in Error{ message = queryErrorMessage, locations = [location], path = [] }
 queryError (UnknownInputType variableDefinition) =
-    let Full.VariableDefinition variableName variableTypeName _ location = variableDefinition
+    let Full.VariableDefinition _ variableTypeName _ location = variableDefinition
         queryErrorMessage = Text.concat
-            [ "Variable \""
+            [ "Variable "
-            , variableName
+            , Text.pack $ showVariableName variableDefinition
-            , "\" has unknown type \""
+            , " has unknown type "
             , Text.pack $ show variableTypeName
-            , "\"."
+            , "."
             ]
      in Error{ message = queryErrorMessage, locations = [location], path = [] }
 
@@ -375,6 +387,7 @@ executeField objectValue fields (viewResolver -> resolverPair) errorPath =
         , Handler (resolverHandler fieldLocation)
         ]
   where
+    fieldErrorPath = fieldsSegment fields : errorPath
     inputCoercionHandler :: (MonadCatch m, Serialize a)
         => Full.Location
         -> InputCoercionException
@@ -402,17 +415,16 @@ executeField objectValue fields (viewResolver -> resolverPair) errorPath =
              then throwM e
              else returnError newError
     exceptionHandler errorLocation e =
-        let newPath = fieldsSegment fields : errorPath
+        let newError = constructError e errorLocation fieldErrorPath
-            newError = constructError e errorLocation newPath
          in if Out.isNonNullType fieldType
-             then throwM $ FieldException errorLocation newPath e
+             then throwM $ FieldException errorLocation fieldErrorPath e
              else returnError newError
     returnError newError = tell (Seq.singleton newError) >> pure null
     go fieldName inputArguments = do
         argumentValues <- coerceArgumentValues argumentTypes inputArguments
         resolvedValue <-
            resolveFieldValue resolveFunction objectValue fieldName argumentValues
-        completeValue fieldType fields errorPath resolvedValue
+        completeValue fieldType fields fieldErrorPath resolvedValue
     (resolverField, resolveFunction) = resolverPair
     Out.Field _ fieldType argumentTypes = resolverField
 
@@ -445,6 +457,7 @@ resolveAbstractType abstractType values'
             _ -> pure Nothing
     | otherwise = pure Nothing
 
+-- https://spec.graphql.org/October2021/#sec-Value-Completion
 completeValue :: (MonadCatch m, Serialize a)
     => Out.Type m
     -> NonEmpty (Transform.Field m)
@@ -454,12 +467,12 @@ completeValue :: (MonadCatch m, Serialize a)
 completeValue (Out.isNonNullType -> False) _ _ Type.Null =
     pure null
 completeValue outputType@(Out.ListBaseType listType) fields errorPath (Type.List list)
-    = foldM go (0, []) list >>= coerceResult outputType . List . snd
+    = foldM go Vector.empty list >>= coerceResult outputType . List . Vector.toList
   where
-    go (index, accumulator) listItem = do
+    go accumulator listItem =
-        let updatedPath = Index index : errorPath
+        let updatedPath = Index (Vector.length accumulator) : errorPath
-        completedValue <- completeValue listType fields updatedPath listItem
+         in Vector.snoc accumulator
-        pure (index + 1, completedValue : accumulator)
+            <$> completeValue listType fields updatedPath listItem
 completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Int int) =
     coerceResult outputType $ Int int
 completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Boolean boolean) =
@@ -476,8 +489,7 @@ completeValue outputType@(Out.EnumBaseType enumType) _ _ (Type.Enum enum) =
             $ ValueCompletionException (show outputType)
             $ Type.Enum enum
 completeValue (Out.ObjectBaseType objectType) fields errorPath result
-    = executeSelectionSet (mergeSelectionSets fields) objectType result
+    = executeSelectionSet (mergeSelectionSets fields) objectType result errorPath
-    $ fieldsSegment fields : errorPath
 completeValue outputType@(Out.InterfaceBaseType interfaceType) fields errorPath result
     | Type.Object objectMap <- result = do
         let abstractType = Type.Internal.AbstractInterfaceType interfaceType
@@ -544,33 +556,24 @@ coerceArgumentValues argumentDefinitions argumentValues =
                     $ Just inputValue
                 | otherwise -> throwM
                     $ InputCoercionException (Text.unpack argumentName) variableType Nothing
+
     matchFieldValues' = matchFieldValues coerceArgumentValue
         $ Full.node <$> argumentValues
-    coerceArgumentValue inputType (Transform.Int integer) =
+
-        coerceInputLiteral inputType (Type.Int integer)
+    coerceArgumentValue inputType transform =
-    coerceArgumentValue inputType (Transform.Boolean boolean) =
+      coerceInputLiteral inputType $ extractArgumentValue transform
-        coerceInputLiteral inputType (Type.Boolean boolean)
+
-    coerceArgumentValue inputType (Transform.String string) =
+    extractArgumentValue (Transform.Int integer) = Type.Int integer
-        coerceInputLiteral inputType (Type.String string)
+    extractArgumentValue (Transform.Boolean boolean) = Type.Boolean boolean
-    coerceArgumentValue inputType (Transform.Float float) =
+    extractArgumentValue (Transform.String string) = Type.String string
-        coerceInputLiteral inputType (Type.Float float)
+    extractArgumentValue (Transform.Float float) = Type.Float float
-    coerceArgumentValue inputType (Transform.Enum enum) =
+    extractArgumentValue (Transform.Enum enum) = Type.Enum enum
-        coerceInputLiteral inputType (Type.Enum enum)
+    extractArgumentValue Transform.Null = Type.Null
-    coerceArgumentValue inputType Transform.Null
+    extractArgumentValue (Transform.List list) =
-        | In.isNonNullType inputType = Nothing
+      Type.List $ extractArgumentValue <$> list
-        | otherwise = coerceInputLiteral inputType Type.Null
+    extractArgumentValue (Transform.Object object) =
-    coerceArgumentValue (In.ListBaseType inputType) (Transform.List list) =
+      Type.Object $ extractArgumentValue <$> object
-        let coerceItem = coerceArgumentValue inputType
+    extractArgumentValue (Transform.Variable variable) = variable
-         in Type.List <$> 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
 
 collectFields :: Monad m
     => Out.ObjectType m

src/Language/GraphQL/Execute/Coerce.hs

@@ -5,7 +5,6 @@
 {-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ViewPatterns #-}
-{-# LANGUAGE CPP #-}
 
 -- | Types and functions used for input and result coercion.
 module Language.GraphQL.Execute.Coerce
@@ -16,10 +15,6 @@ module Language.GraphQL.Execute.Coerce
     , matchFieldValues
     ) where
 
-#ifdef WITH_JSON
-import qualified Data.Aeson as Aeson
-import Data.Scientific (toBoundedInteger, toRealFloat)
-#endif
 import Data.Int (Int32)
 import Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as HashMap
@@ -227,69 +222,3 @@ instance Serialize Type.Value where
         $ HashMap.fromList
         $ OrderedMap.toList object
     serialize _ _ = Nothing
-
-#ifdef WITH_JSON
-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.object
-        $ OrderedMap.toList
-        $ Aeson.toJSON <$> object
-    serialize _ _ = Nothing
-    null = Aeson.Null
-
-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
-#endif

src/Language/GraphQL/TH.hs

@@ -21,7 +21,7 @@ stripIndentation code = reverse
     indent count (' ' : xs) = indent (count - 1) xs
     indent _ xs = xs
     withoutLeadingNewlines = dropNewlines code
-    dropNewlines = dropWhile (== '\n')
+    dropNewlines = dropWhile $ flip any ['\n', '\r'] . (==)
     spaces = length $ takeWhile (== ' ') withoutLeadingNewlines
 
 -- | Removes leading and trailing newlines. Indentation of the first line is

src/Language/GraphQL/Type/Definition.hs

@@ -18,6 +18,8 @@ module Language.GraphQL.Type.Definition
     , float
     , id
     , int
+    , showNonNullType
+    , showNonNullListType
     , selection
     , string
     ) where
@@ -207,3 +209,11 @@ include = handle include'
             (Just (Boolean True)) -> Include directive'
             _ -> Skip
     include' directive' = Continue directive'
+
+showNonNullType :: Show a => a -> String
+showNonNullType = (++ "!") . show
+
+showNonNullListType :: Show a => a -> String
+showNonNullListType listType =
+    let representation = show listType
+     in concat ["[", representation, "]!"]

src/Language/GraphQL/Type/In.hs

@@ -66,10 +66,11 @@ instance Show Type where
     show (NamedEnumType enumType) = show enumType
     show (NamedInputObjectType inputObjectType) = show inputObjectType
     show (ListType baseType) = concat ["[", show baseType, "]"]
-    show (NonNullScalarType scalarType) = '!' : show scalarType
+    show (NonNullScalarType scalarType) = Definition.showNonNullType scalarType
-    show (NonNullEnumType enumType) = '!' : show enumType
+    show (NonNullEnumType enumType) = Definition.showNonNullType enumType
-    show (NonNullInputObjectType inputObjectType) = '!' : show inputObjectType
+    show (NonNullInputObjectType inputObjectType) =
-    show (NonNullListType baseType) = concat ["![", show baseType, "]"]
+        Definition.showNonNullType inputObjectType
+    show (NonNullListType baseType) = Definition.showNonNullListType baseType
 
 -- | Field argument definition.
 data Argument = Argument (Maybe Text) Type (Maybe Definition.Value)

src/Language/GraphQL/Type/Out.hs

@@ -115,12 +115,12 @@ instance forall a. Show (Type a) where
     show (NamedInterfaceType interfaceType) = show interfaceType
     show (NamedUnionType unionType) = show unionType
     show (ListType baseType) = concat ["[", show baseType, "]"]
-    show (NonNullScalarType scalarType) = '!' : show scalarType
+    show (NonNullScalarType scalarType) = showNonNullType scalarType
-    show (NonNullEnumType enumType) = '!' : show enumType
+    show (NonNullEnumType enumType) = showNonNullType enumType
-    show (NonNullObjectType inputObjectType) = '!' : show inputObjectType
+    show (NonNullObjectType inputObjectType) = showNonNullType inputObjectType
-    show (NonNullInterfaceType interfaceType) = '!' : show interfaceType
+    show (NonNullInterfaceType interfaceType) = showNonNullType interfaceType
-    show (NonNullUnionType unionType) = '!' : show unionType
+    show (NonNullUnionType unionType) = showNonNullType unionType
-    show (NonNullListType baseType) = concat ["![", show baseType, "]"]
+    show (NonNullListType baseType) = showNonNullListType baseType
 
 -- | Matches either 'NamedScalarType' or 'NonNullScalarType'.
 pattern ScalarBaseType :: forall m. ScalarType -> Type m

src/Language/GraphQL/Validate/Rules.hs

@@ -2,11 +2,13 @@
    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 DataKinds #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE ViewPatterns #-}
 
 -- | This module contains default rules defined in the GraphQL specification.
@@ -54,13 +56,14 @@ import Data.HashMap.Strict (HashMap)
 import Data.HashSet (HashSet)
 import qualified Data.HashSet as HashSet
 import Data.List (groupBy, sortBy, sortOn)
-import Data.Maybe (catMaybes, fromMaybe, isJust, isNothing, mapMaybe)
+import Data.Maybe (fromMaybe, isJust, isNothing, mapMaybe)
 import Data.List.NonEmpty (NonEmpty(..))
 import Data.Ord (comparing)
 import Data.Sequence (Seq(..), (|>))
 import qualified Data.Sequence as Seq
 import Data.Text (Text)
 import qualified Data.Text as Text
+import GHC.Records (HasField(..))
 import qualified Language.GraphQL.AST.Document as Full
 import qualified Language.GraphQL.Type.Definition as Definition
 import qualified Language.GraphQL.Type.Internal as Type
@@ -618,6 +621,10 @@ noUndefinedVariablesRule =
         , "\"."
         ]
 
+-- Used to find the difference between defined and used variables. The first
+-- argument are variables defined in the operation, the second argument are
+-- variables used in the query. It should return the difference between these
+-- 2 sets.
 type UsageDifference
     = HashMap Full.Name [Full.Location]
     -> HashMap Full.Name [Full.Location]
@@ -664,11 +671,17 @@ variableUsageDifference difference errorMessage = OperationDefinitionRule $ \cas
         = filterSelections' selections
         >>= lift . mapReaderT (<> mapDirectives directives') . pure
     findDirectiveVariables (Full.Directive _ arguments _) = mapArguments arguments
-    mapArguments = Seq.fromList . mapMaybe findArgumentVariables
+    mapArguments = Seq.fromList . (>>= findArgumentVariables)
     mapDirectives = foldMap findDirectiveVariables
-    findArgumentVariables (Full.Argument _ Full.Node{ node = Full.Variable value', ..} _) =
+
-        Just (value', [location])
+    findArgumentVariables (Full.Argument _ value _) = findNodeVariables value
-    findArgumentVariables _ = Nothing
+    findNodeVariables Full.Node{ node = value, ..} = findValueVariables location value
+
+    findValueVariables location (Full.Variable value') = [(value', [location])]
+    findValueVariables _ (Full.List values) = values >>= findNodeVariables
+    findValueVariables _ (Full.Object fields) = fields
+        >>= findNodeVariables . getField @"value"
+    findValueVariables _ _ = []
     makeError operationName (variableName, locations') = Error
         { message = errorMessage operationName variableName
         , locations = locations'
@@ -1551,9 +1564,9 @@ valuesOfCorrectTypeRule = ValueRule go constGo
     toConst Full.Null = Just Full.ConstNull
     toConst (Full.Enum enum) = Just $ Full.ConstEnum enum
     toConst (Full.List values) =
-        Just $ Full.ConstList $ catMaybes $ toConstNode <$> values
+        Just $ Full.ConstList $ mapMaybe toConstNode values
     toConst (Full.Object fields) = Just $ Full.ConstObject
-        $ catMaybes $ constObjectField <$> fields
+        $ mapMaybe constObjectField fields
     constObjectField Full.ObjectField{..}
         | Just constValue <- toConstNode value =
             Just $ Full.ObjectField name constValue location

src/Test/Hspec/GraphQL.hs

@@ -1,49 +0,0 @@
-{- 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 CPP #-}
-
-#ifdef WITH_JSON
-{-# 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"
-#else
-module Test.Hspec.GraphQL
-    (
-    ) where
-#endif

tests/Language/GraphQL/AST/Arbitrary.hs

@@ -0,0 +1,99 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module Language.GraphQL.AST.Arbitrary where
+
+import qualified Language.GraphQL.AST.Document as Doc
+import Test.QuickCheck.Arbitrary (Arbitrary (arbitrary))
+import Test.QuickCheck (oneof, elements, listOf, resize, NonEmptyList (..))
+import Test.QuickCheck.Gen (Gen (..))
+import Data.Text (Text, pack)
+
+newtype AnyPrintableChar = AnyPrintableChar { getAnyPrintableChar :: Char } deriving (Eq, Show)
+
+alpha :: String
+alpha = ['a'..'z'] <> ['A'..'Z']
+
+num :: String
+num = ['0'..'9']
+
+instance Arbitrary AnyPrintableChar where
+    arbitrary = AnyPrintableChar <$> elements chars
+        where
+           chars = alpha <> num <> ['_'] 
+
+newtype AnyPrintableText = AnyPrintableText { getAnyPrintableText :: Text } deriving (Eq, Show)
+
+instance Arbitrary AnyPrintableText where
+    arbitrary = do
+        nonEmptyStr <- getNonEmpty <$> (arbitrary :: Gen (NonEmptyList AnyPrintableChar))
+        pure $ AnyPrintableText (pack $ map getAnyPrintableChar nonEmptyStr)
+
+-- https://spec.graphql.org/June2018/#Name
+newtype AnyName = AnyName { getAnyName :: Text } deriving (Eq, Show)
+
+instance Arbitrary AnyName where
+    arbitrary = do
+        firstChar <- elements $ alpha <> ['_']
+        rest <- (arbitrary :: Gen [AnyPrintableChar])
+        pure $ AnyName (pack $ firstChar : map getAnyPrintableChar rest)
+
+newtype AnyLocation = AnyLocation { getAnyLocation :: Doc.Location } deriving (Eq, Show)
+
+instance Arbitrary AnyLocation where
+    arbitrary = AnyLocation <$> (Doc.Location <$> arbitrary <*> arbitrary)
+
+newtype AnyNode a = AnyNode { getAnyNode :: Doc.Node a } deriving (Eq, Show)
+
+instance Arbitrary a => Arbitrary (AnyNode a) where
+    arbitrary = do
+        (AnyLocation location') <- arbitrary
+        node' <- flip Doc.Node location' <$> arbitrary
+        pure $ AnyNode node'
+
+newtype AnyObjectField a = AnyObjectField { getAnyObjectField :: Doc.ObjectField a } deriving (Eq, Show)
+
+instance Arbitrary a => Arbitrary (AnyObjectField a) where
+    arbitrary = do
+        name' <- getAnyName <$> arbitrary
+        value' <- getAnyNode <$> arbitrary
+        location' <- getAnyLocation <$> arbitrary
+        pure $ AnyObjectField $ Doc.ObjectField name' value' location'
+
+newtype AnyValue = AnyValue { getAnyValue :: Doc.Value } deriving (Eq, Show)
+
+instance Arbitrary AnyValue where
+    arbitrary = AnyValue <$> oneof
+        [ variableGen
+        , Doc.Int <$> arbitrary
+        , Doc.Float <$> arbitrary
+        , Doc.String <$> (getAnyPrintableText <$> arbitrary)
+        , Doc.Boolean <$> arbitrary
+        , MkGen $ \_ _ -> Doc.Null
+        , Doc.Enum <$> (getAnyName <$> arbitrary)
+        , Doc.List <$> listGen
+        , Doc.Object <$> objectGen
+        ]
+            where
+                variableGen :: Gen Doc.Value
+                variableGen = Doc.Variable <$> (getAnyName <$> arbitrary)
+                listGen :: Gen [Doc.Node Doc.Value]
+                listGen = (resize 5 . listOf) nodeGen
+                nodeGen = do
+                    node' <- getAnyNode <$> (arbitrary :: Gen (AnyNode AnyValue))
+                    pure (getAnyValue <$> node')
+                objectGen :: Gen [Doc.ObjectField Doc.Value]
+                objectGen = resize 1 $ do
+                    list <- getNonEmpty <$> (arbitrary :: Gen (NonEmptyList (AnyObjectField AnyValue)))
+                    pure $ map (fmap getAnyValue . getAnyObjectField) list
+
+newtype AnyArgument a = AnyArgument { getAnyArgument :: Doc.Argument } deriving (Eq, Show)
+
+instance Arbitrary a => Arbitrary (AnyArgument a) where
+    arbitrary = do
+        name' <- getAnyName <$> arbitrary
+        (AnyValue value') <- arbitrary
+        (AnyLocation location') <- arbitrary
+        pure $ AnyArgument $ Doc.Argument name' (Doc.Node value' location') location'
+
+printArgument :: AnyArgument AnyValue -> Text
+printArgument (AnyArgument (Doc.Argument name' (Doc.Node value' _) _)) = name' <> ": " <> (pack . show) value'

tests/Language/GraphQL/AST/DocumentSpec.hs

@@ -18,3 +18,9 @@ spec = do
                     ]
                 expected = "{ field1: 1.2, field2: null }"
              in show object `shouldBe` expected
+
+    describe "Description" $
+        it "keeps content when merging with no description" $
+            let expected = Description $ Just "Left description"
+                actual = expected <> Description Nothing
+             in actual `shouldBe` expected

tests/Language/GraphQL/AST/EncoderSpec.hs

@@ -4,6 +4,7 @@ module Language.GraphQL.AST.EncoderSpec
     ( spec
     ) where
 
+import Data.List.NonEmpty (NonEmpty(..))
 import qualified Language.GraphQL.AST.Document as Full
 import Language.GraphQL.AST.Encoder
 import Language.GraphQL.TH
@@ -173,3 +174,96 @@ spec = do
                 |] '\n'
                 actual = definition pretty operation
              in actual `shouldBe` expected
+
+    describe "operationType" $
+        it "produces lowercase mutation operation type" $
+            let actual = operationType pretty Full.Mutation
+             in actual `shouldBe` "mutation"
+
+    describe "typeSystemDefinition" $ do
+        it "produces a schema with an indented operation type definition" $
+            let queryType = Full.OperationTypeDefinition Full.Query "QueryRootType"
+                mutationType = Full.OperationTypeDefinition Full.Mutation "MutationType"
+                operations = queryType :| pure mutationType
+                definition' = Full.SchemaDefinition [] operations
+                expected = Text.Lazy.snoc [gql|
+                  schema {
+                    query: QueryRootType
+                    mutation: MutationType
+                  }
+                |] '\n'
+                actual = typeSystemDefinition pretty definition'
+             in actual `shouldBe` expected
+
+        it "encodes a scalar type definition" $
+            let uuidType = Full.ScalarTypeDefinition mempty "UUID" mempty
+                definition' = Full.TypeDefinition uuidType
+                expected = "scalar UUID"
+                actual = typeSystemDefinition pretty definition'
+             in actual `shouldBe` expected
+
+        it "encodes an interface definition" $
+            let someType = Full.TypeNamed "String"
+                argument = Full.InputValueDefinition mempty "arg" someType Nothing mempty
+                arguments = Full.ArgumentsDefinition [argument]
+                definition' = Full.TypeDefinition
+                    $ Full.InterfaceTypeDefinition mempty "UUID" mempty
+                    $ pure
+                    $ Full.FieldDefinition mempty "value" arguments someType mempty
+                expected = [gql|
+                  interface UUID {
+                    value(arg: String): String
+                  }
+                |]
+                actual = typeSystemDefinition pretty definition'
+             in actual `shouldBe` expected
+
+        it "encodes an union definition" $
+            let definition' = Full.TypeDefinition
+                    $ Full.UnionTypeDefinition mempty "SearchResult" mempty
+                    $ Full.UnionMemberTypes ["Photo", "Person"]
+                expected = [gql|
+                  union SearchResult =
+                    | Photo
+                    | Person
+                |]
+                actual = typeSystemDefinition pretty definition'
+             in actual `shouldBe` expected
+
+        it "encodes an enum definition" $
+            let values =
+                    [ Full.EnumValueDefinition mempty "NORTH" mempty
+                    , Full.EnumValueDefinition mempty "EAST" mempty
+                    , Full.EnumValueDefinition mempty "SOUTH" mempty
+                    , Full.EnumValueDefinition mempty "WEST" mempty
+                    ]
+                definition' = Full.TypeDefinition
+                    $ Full.EnumTypeDefinition mempty "Direction" mempty values
+                expected = [gql|
+                  enum Direction {
+                    NORTH
+                    EAST
+                    SOUTH
+                    WEST
+                  }
+                |]
+                actual = typeSystemDefinition pretty definition'
+             in actual `shouldBe` expected
+
+        it "encodes an input type" $
+            let intType = Full.TypeNonNull $ Full.NonNullTypeNamed "Int"
+                stringType = Full.TypeNamed "String"
+                fields =
+                    [ Full.InputValueDefinition mempty "a" stringType Nothing mempty
+                    , Full.InputValueDefinition mempty "b" intType Nothing mempty
+                    ]
+                definition' = Full.TypeDefinition
+                    $ Full.InputObjectTypeDefinition mempty "ExampleInputObject" mempty fields
+                expected = [gql|
+                  input ExampleInputObject {
+                    a: String
+                    b: Int!
+                  }
+                |]
+                actual = typeSystemDefinition pretty definition'
+             in actual `shouldBe` expected

tests/Language/GraphQL/AST/ParserSpec.hs

@@ -5,19 +5,24 @@ module Language.GraphQL.AST.ParserSpec
     ) where
 
 import Data.List.NonEmpty (NonEmpty(..))
+import Data.Text (Text)
+import qualified Data.Text as Text
 import Language.GraphQL.AST.Document
 import qualified Language.GraphQL.AST.DirectiveLocation as DirLoc
 import Language.GraphQL.AST.Parser
 import Language.GraphQL.TH
-import Test.Hspec (Spec, describe, it)
+import Test.Hspec (Spec, describe, it, context)
 import Test.Hspec.Megaparsec (shouldParse, shouldFailOn, shouldSucceedOn)
 import Text.Megaparsec (parse)
+import Test.QuickCheck (property, NonEmptyList (..), mapSize)
+import Language.GraphQL.AST.Arbitrary
 
 spec :: Spec
 spec = describe "Parser" $ do
     it "accepts BOM header" $
         parse document "" `shouldSucceedOn` "\xfeff{foo}"
 
+    context "Arguments" $ do
        it "accepts block strings as argument" $
            parse document "" `shouldSucceedOn` [gql|{
                  hello(text: """Argument""")
@@ -28,6 +33,26 @@ spec = describe "Parser" $ do
                  hello(text: "Argument")
                }|]
 
+       it "accepts int as argument1" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 user(id: 4)
+               }|]
+
+       it "accepts boolean as argument" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 hello(flag: true) { field1 }
+               }|]
+
+       it "accepts float as argument" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 body(height: 172.5) { height }
+               }|]
+
+       it "accepts empty list as argument" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 query(list: []) { field1 }
+               }|]
+
        it "accepts two required arguments" $
            parse document "" `shouldSucceedOn` [gql|
                mutation auth($username: String!, $password: String!){
@@ -46,6 +71,13 @@ spec = describe "Parser" $ do
                  test(username: """username""", password: """password""")
                }|]
  
+       it "accepts any arguments" $ mapSize (const 10) $ property $ \xs ->
+            let
+                query' :: Text
+                arguments = map printArgument $ getNonEmpty (xs :: NonEmptyList (AnyArgument AnyValue))
+                query' = "query(" <> Text.intercalate ", " arguments <> ")" in
+            parse document "" `shouldSucceedOn` ("{ " <> query' <> " }")
+
     it "parses minimal schema definition" $
         parse document "" `shouldSucceedOn` [gql|schema { query: Query }|]
 
@@ -95,16 +127,6 @@ spec = describe "Parser" $ do
             }
         |]
 
-    it "parses minimal enum type definition" $
-        parse document "" `shouldSucceedOn` [gql|
-            enum Direction {
-              NORTH
-              EAST
-              SOUTH
-              WEST
-            }
-        |]
-
     it "parses minimal input object type definition" $
         parse document "" `shouldSucceedOn` [gql|
             input Point2D {
@@ -202,6 +224,13 @@ spec = describe "Parser" $ do
             }
         |]
 
+    it "rejects empty selection set" $
+       parse document "" `shouldFailOn` [gql|
+            query {
+              innerField {}
+            }
+        |]
+
     it "parses documents beginning with a comment" $
         parse document "" `shouldSucceedOn` [gql|
             """

tests/Language/GraphQL/ExecuteSpec.hs

@@ -2,13 +2,18 @@
    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 DuplicateRecordFields #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE QuasiQuotes #-}
+
 module Language.GraphQL.ExecuteSpec
     ( spec
     ) where
 
-import Control.Exception (Exception(..), SomeException)
+import Control.Exception (Exception(..))
 import Control.Monad.Catch (throwM)
 import Data.Conduit
 import Data.HashMap.Strict (HashMap)
@@ -20,12 +25,23 @@ import Language.GraphQL.Error
 import Language.GraphQL.Execute (execute)
 import Language.GraphQL.TH
 import qualified Language.GraphQL.Type.Schema as Schema
+import qualified Language.GraphQL.Type as Type
 import Language.GraphQL.Type
 import qualified Language.GraphQL.Type.In as In
 import qualified Language.GraphQL.Type.Out as Out
 import Prelude hiding (id)
 import Test.Hspec (Spec, context, describe, it, shouldBe)
-import Text.Megaparsec (parse)
+import Text.Megaparsec (parse, errorBundlePretty)
+import Schemas.HeroSchema (heroSchema)
+import Data.Maybe (fromJust)
+import qualified Data.Sequence as Seq
+import Data.Text (Text)
+import qualified Data.Text as Text
+import Test.Hspec.Expectations
+    ( Expectation
+    , expectationFailure
+    )
+import Data.Either (fromRight)
 
 data PhilosopherException = PhilosopherException
     deriving Show
@@ -36,7 +52,7 @@ instance Exception PhilosopherException where
         ResolverException resolverException <- fromException e
         cast resolverException
 
-philosopherSchema :: Schema (Either SomeException)
+philosopherSchema :: Schema IO
 philosopherSchema =
     schemaWithTypes Nothing queryType Nothing subscriptionRoot extraTypes mempty
   where
@@ -46,12 +62,14 @@ philosopherSchema =
         , Schema.ObjectType bookCollectionType
         ]
 
-queryType :: Out.ObjectType (Either SomeException)
+queryType :: Out.ObjectType IO
 queryType = Out.ObjectType "Query" Nothing []
     $ HashMap.fromList
     [ ("philosopher", ValueResolver philosopherField philosopherResolver)
-    , ("genres", ValueResolver genresField genresResolver)
+    , ("throwing", ValueResolver throwingField throwingResolver)
     , ("count", ValueResolver countField countResolver)
+    , ("sequence", ValueResolver sequenceField sequenceResolver)
+    , ("withInputObject", ValueResolver withInputObjectField withInputObjectResolver)
     ]
   where
     philosopherField =
@@ -59,17 +77,35 @@ queryType = Out.ObjectType "Query" Nothing []
         $ HashMap.singleton "id"
         $ In.Argument Nothing (In.NamedScalarType id) Nothing
     philosopherResolver = pure $ Object mempty
-    genresField =
+    throwingField =
         let fieldType = Out.ListType $ Out.NonNullScalarType string
          in Out.Field Nothing fieldType HashMap.empty
-    genresResolver :: Resolve (Either SomeException)
+    throwingResolver :: Resolve IO
-    genresResolver = throwM PhilosopherException
+    throwingResolver = throwM PhilosopherException
     countField =
         let fieldType = Out.NonNullScalarType int
          in Out.Field Nothing fieldType HashMap.empty
     countResolver = pure ""
+    sequenceField =
+        let fieldType = Out.ListType $ Out.NonNullScalarType int
+         in Out.Field Nothing fieldType HashMap.empty
+    sequenceResolver = pure intSequence
+    withInputObjectResolver = pure $ Type.Int 0
+    withInputObjectField =
+        Out.Field Nothing (Out.NonNullScalarType int) $ HashMap.fromList
+            [("values", In.Argument Nothing withInputObjectArgumentType Nothing)]
+    withInputObjectArgumentType = In.NonNullListType
+        $ In.NonNullInputObjectType inputObjectType
 
-musicType :: Out.ObjectType (Either SomeException)
+inputObjectType :: In.InputObjectType
+inputObjectType = In.InputObjectType "InputObject" Nothing $
+    HashMap.singleton "name" $
+        In.InputField Nothing (In.NonNullScalarType int) Nothing
+
+intSequence :: Value
+intSequence = Type.List [Type.Int 1, Type.Int 2, Type.Int 3]
+
+musicType :: Out.ObjectType IO
 musicType = Out.ObjectType "Music" Nothing []
     $ HashMap.fromList resolvers
   where
@@ -79,7 +115,7 @@ musicType = Out.ObjectType "Music" Nothing []
     instrumentResolver = pure $ String "piano"
     instrumentField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
 
-poetryType :: Out.ObjectType (Either SomeException)
+poetryType :: Out.ObjectType IO
 poetryType = Out.ObjectType "Poetry" Nothing []
     $ HashMap.fromList resolvers
   where
@@ -89,10 +125,10 @@ poetryType = Out.ObjectType "Poetry" Nothing []
     genreResolver = pure $ String "Futurism"
     genreField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
 
-interestType :: Out.UnionType (Either SomeException)
+interestType :: Out.UnionType IO
 interestType = Out.UnionType "Interest" Nothing [musicType, poetryType]
 
-philosopherType :: Out.ObjectType (Either SomeException)
+philosopherType :: Out.ObjectType IO
 philosopherType = Out.ObjectType "Philosopher" Nothing []
     $ HashMap.fromList resolvers
   where
@@ -133,14 +169,14 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
         = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
     firstLanguageResolver = pure Null
 
-workType :: Out.InterfaceType (Either SomeException)
+workType :: Out.InterfaceType IO
 workType = Out.InterfaceType "Work" Nothing []
     $ HashMap.fromList fields
   where
     fields = [("title", titleField)]
     titleField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
 
-bookType :: Out.ObjectType (Either SomeException)
+bookType :: Out.ObjectType IO
 bookType = Out.ObjectType "Book" Nothing [workType]
     $ HashMap.fromList resolvers
   where
@@ -150,7 +186,7 @@ bookType = Out.ObjectType "Book" Nothing [workType]
     titleField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
     titleResolver = pure "Also sprach Zarathustra: Ein Buch für Alle und Keinen"
 
-bookCollectionType :: Out.ObjectType (Either SomeException)
+bookCollectionType :: Out.ObjectType IO
 bookCollectionType = Out.ObjectType "Book" Nothing [workType]
     $ HashMap.fromList resolvers
   where
@@ -160,7 +196,7 @@ bookCollectionType = Out.ObjectType "Book" Nothing [workType]
     titleField = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
     titleResolver = pure "The Three Critiques"
 
-subscriptionType :: Out.ObjectType (Either SomeException)
+subscriptionType :: Out.ObjectType IO
 subscriptionType = Out.ObjectType "Subscription" Nothing []
     $ HashMap.singleton "newQuote"
     $ EventStreamResolver quoteField (pure $ Object mempty)
@@ -169,7 +205,7 @@ subscriptionType = Out.ObjectType "Subscription" Nothing []
     quoteField =
         Out.Field Nothing (Out.NonNullObjectType quoteType) HashMap.empty
 
-quoteType :: Out.ObjectType (Either SomeException)
+quoteType :: Out.ObjectType IO
 quoteType = Out.ObjectType "Quote" Nothing []
     $ HashMap.singleton "quote"
     $ ValueResolver quoteField
@@ -178,7 +214,7 @@ quoteType = Out.ObjectType "Quote" Nothing []
     quoteField =
         Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
 
-schoolType :: EnumType
+schoolType :: Type.EnumType
 schoolType = EnumType "School" Nothing $ HashMap.fromList
     [ ("NOMINALISM", EnumValue Nothing)
     , ("REALISM", EnumValue Nothing)
@@ -186,12 +222,48 @@ schoolType = EnumType "School" Nothing $ HashMap.fromList
     ]
 
 type EitherStreamOrValue = Either
-    (ResponseEventStream (Either SomeException) Value)
+    (ResponseEventStream IO Type.Value)
-    (Response Value)
+    (Response Type.Value)
 
-execute' :: Document -> Either SomeException EitherStreamOrValue
+-- Asserts that a query resolves to a value.
-execute' =
+shouldResolveTo :: Text.Text -> Response Type.Value -> Expectation
-    execute philosopherSchema Nothing (mempty :: HashMap Name Value)
+shouldResolveTo querySource expected =
+    case parse document "" querySource of
+        (Right parsedDocument) ->
+            execute philosopherSchema Nothing (mempty :: HashMap Name Type.Value) parsedDocument >>= go
+        (Left errorBundle) -> expectationFailure $ errorBundlePretty errorBundle
+  where
+    go = \case
+        Right result -> shouldBe result expected
+        Left _ -> expectationFailure
+            "the query is expected to resolve to a value, but it resolved to an event stream"
+
+-- Asserts that the executor produces an error that starts with a string.
+shouldContainError :: Either (ResponseEventStream IO Type.Value) (Response Type.Value)
+    -> Text
+    -> Expectation
+shouldContainError streamOrValue expected =
+    case streamOrValue of
+        Right response -> respond response
+        Left _ -> expectationFailure
+            "the query is expected to resolve to a value, but it resolved to an event stream"
+  where
+    startsWith :: Text.Text -> Text.Text -> Bool
+    startsWith xs ys = Text.take (Text.length ys) xs == ys
+    respond :: Response Type.Value -> Expectation
+    respond Response{ errors }
+        | any ((`startsWith` expected) . message) errors = pure ()
+        | otherwise = expectationFailure
+            "the query is expected to execute with errors, but the response doesn't contain any errors"
+
+parseAndExecute :: Schema IO
+    -> Maybe Text
+    -> HashMap Name Type.Value
+    -> Text
+    -> IO (Either (ResponseEventStream IO Type.Value) (Response Type.Value))
+parseAndExecute schema' operation variables
+    = either (pure . parseError) (execute schema' operation variables)
+    . parse document ""
 
 spec :: Spec
 spec =
@@ -207,9 +279,7 @@ spec =
               }
             |]
                 expected = Response (Object mempty) mempty
-                Right (Right actual) = either (pure . parseError) execute'
+             in sourceQuery `shouldResolveTo` expected
-                    $ parse document "" sourceQuery
-             in actual `shouldBe` expected
 
         context "Query" $ do
             it "skips unknown fields" $
@@ -219,9 +289,8 @@ spec =
                         $ HashMap.singleton "firstName"
                         $ String "Friedrich"
                     expected = Response data'' mempty
-                    Right (Right actual) = either (pure . parseError) execute'
+                    sourceQuery = "{ philosopher { firstName surname } }"
-                        $ parse document "" "{ philosopher { firstName surname } }"
+                in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
             it "merges selections" $
                 let data'' = Object
                         $ HashMap.singleton "philosopher"
@@ -231,50 +300,96 @@ spec =
                             , ("lastName", String "Nietzsche")
                             ]
                     expected = Response data'' mempty
-                    Right (Right actual) = either (pure . parseError) execute'
+                    sourceQuery = "{ philosopher { firstName } philosopher { lastName } }"
-                        $ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
+                in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
 
             it "errors on invalid output enum values" $
                 let data'' = Object $ HashMap.singleton "philosopher" Null
                     executionErrors = pure $ Error
                         { message =
-                            "Value completion error. Expected type !School, found: EXISTENTIALISM."
+                            "Value completion error. Expected type School!, found: EXISTENTIALISM."
                         , locations = [Location 1 17]
                         , path = [Segment "philosopher", Segment "school"]
                         }
                     expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
+                    sourceQuery = "{ philosopher { school } }"
-                        $ parse document "" "{ philosopher { school } }"
+                 in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
 
             it "gives location information for non-null unions" $
                 let data'' = Object $ HashMap.singleton "philosopher" Null
                     executionErrors = pure $ Error
                         { message =
-                            "Value completion error. Expected type !Interest, found: { instrument: \"piano\" }."
+                            "Value completion error. Expected type Interest!, found: { instrument: \"piano\" }."
                         , locations = [Location 1 17]
                         , path = [Segment "philosopher", Segment "interest"]
                         }
                     expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
+                    sourceQuery = "{ philosopher { interest } }"
-                        $ parse document "" "{ philosopher { interest } }"
+                 in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
 
             it "gives location information for invalid interfaces" $
                 let data'' = Object $ HashMap.singleton "philosopher" Null
                     executionErrors = pure $ Error
                         { message
-                            = "Value completion error. Expected type !Work, found:\
+                            = "Value completion error. Expected type Work!, found:\
                             \ { title: \"Also sprach Zarathustra: Ein Buch f\252r Alle und Keinen\" }."
                         , locations = [Location 1 17]
                         , path = [Segment "philosopher", Segment "majorWork"]
                         }
                     expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
+                    sourceQuery = "{ philosopher { majorWork { title } } }"
-                        $ parse document "" "{ philosopher { majorWork { title } } }"
+                 in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
 
+            it "gives location information for failed result coercion" $
+                let data'' = Object $ HashMap.singleton "philosopher" Null
+                    executionErrors = pure $ Error
+                        { message = "Unable to coerce result to Int!."
+                        , locations = [Location 1 26]
+                        , path = [Segment "philosopher", Segment "century"]
+                        }
+                    expected = Response data'' executionErrors
+                    sourceQuery = "{ philosopher(id: \"1\") { century } }"
+                in sourceQuery `shouldResolveTo` expected
+
+            it "gives location information for failed result coercion" $
+                let data'' = Object $ HashMap.singleton "throwing" Null
+                    executionErrors = pure $ Error
+                        { message = "PhilosopherException"
+                        , locations = [Location 1 3]
+                        , path = [Segment "throwing"]
+                        }
+                    expected = Response data'' executionErrors
+                    sourceQuery = "{ throwing }"
+                in sourceQuery `shouldResolveTo` expected
+
+            it "sets data to null if a root field isn't nullable" $
+                let executionErrors = pure $ Error
+                        { message = "Unable to coerce result to Int!."
+                        , locations = [Location 1 3]
+                        , path = [Segment "count"]
+                        }
+                    expected = Response Null executionErrors
+                    sourceQuery = "{ count }"
+                in sourceQuery `shouldResolveTo` expected
+
+            it "detects nullability errors" $
+                let data'' = Object $ HashMap.singleton "philosopher" Null
+                    executionErrors = pure $ Error
+                        { message = "Value completion error. Expected type String!, found: null."
+                        , locations = [Location 1 26]
+                        , path = [Segment "philosopher", Segment "firstLanguage"]
+                        }
+                    expected = Response data'' executionErrors
+                    sourceQuery = "{ philosopher(id: \"1\") { firstLanguage } }"
+                in sourceQuery `shouldResolveTo` expected
+
+            it "returns list elements in the original order" $
+                let data'' = Object $ HashMap.singleton "sequence" intSequence
+                    expected = Response data'' mempty
+                    sourceQuery = "{ sequence }"
+                in sourceQuery `shouldResolveTo` expected
+
+            context "Arguments" $ do
                 it "gives location information for invalid scalar arguments" $
                     let data'' = Object $ HashMap.singleton "philosopher" Null
                         executionErrors = pure $ Error
@@ -284,66 +399,75 @@ spec =
                             , path = [Segment "philosopher"]
                             }
                         expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
+                        sourceQuery = "{ philosopher(id: true) { lastName } }"
-                        $ parse document "" "{ philosopher(id: true) { lastName } }"
+                    in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
 
-            it "gives location information for failed result coercion" $
+                it "puts an object in a list if needed" $
-                let data'' = Object $ HashMap.singleton "philosopher" Null
+                    let data'' = Object $ HashMap.singleton "withInputObject" $ Type.Int 0
+                        expected = Response data'' mempty
+                        sourceQuery = "{ withInputObject(values: { name: 0 }) }"
+                    in sourceQuery `shouldResolveTo` expected
+
+            context "queryError" $ do
+                let namedQuery name = "query " <> name <> " { philosopher(id: \"1\") { interest } }"
+                    twoQueries = namedQuery "A" <> " " <> namedQuery "B"
+
+                it "throws operation name is required error" $ do
+                    let expectedErrorMessage = "Operation name is required"
+                    actual <- parseAndExecute philosopherSchema Nothing mempty twoQueries
+                    actual `shouldContainError` expectedErrorMessage
+
+                it "throws operation not found error" $ do
+                    let expectedErrorMessage = "Operation \"C\" is not found"
+                    actual <- parseAndExecute philosopherSchema (Just "C") mempty twoQueries
+                    actual `shouldContainError` expectedErrorMessage
+
+                it "throws variable coercion error" $ do
+                    let data'' = Null
                         executionErrors = pure $ Error
-                        { message = "Unable to coerce result to !Int."
+                            { message = "Failed to coerce the variable $id: String."
-                        , locations = [Location 1 26]
+                            , locations =[Location 1 7]
-                        , path = [Segment "philosopher", Segment "century"]
+                            , path = []
                             }
                         expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
+                        executeWithVars = execute philosopherSchema Nothing (HashMap.singleton "id" (Type.Int 1))
-                        $ parse document "" "{ philosopher(id: \"1\") { century } }"
+                    Right actual <- either (pure . parseError) executeWithVars
-                in actual `shouldBe` expected
+                        $ parse document "" "query($id: String) { philosopher(id: \"1\") { firstLanguage } }"
+                    actual `shouldBe` expected
 
-            it "gives location information for failed result coercion" $
+                it "throws variable unkown input type error" $
-                let data'' = Object $ HashMap.singleton "genres" Null
+                    let data'' = Null
                         executionErrors = pure $ Error
-                        { message = "PhilosopherException"
+                            { message = "Variable $id has unknown type Cat."
-                        , locations = [Location 1 3]
+                            , locations =[Location 1 7]
-                        , path = [Segment "genres"]
+                            , path = []
                             }
                         expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
+                        sourceQuery = "query($id: Cat) { philosopher(id: \"1\") { firstLanguage } }"
-                        $ parse document "" "{ genres }"
+                     in sourceQuery `shouldResolveTo` expected
-                in actual `shouldBe` expected
 
-            it "sets data to null if a root field isn't nullable" $
+            context "Error path" $ do
-                let executionErrors = pure $ Error
+                let executeHero :: Document -> IO EitherStreamOrValue
-                        { message = "Unable to coerce result to !Int."
+                    executeHero = execute heroSchema Nothing (HashMap.empty :: HashMap Name Type.Value)
-                        , locations = [Location 1 3]
-                        , path = [Segment "count"]
-                        }
-                    expected = Response Null executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ count }"
-                in actual `shouldBe` expected
 
-            it "detects nullability errors" $
+                it "at the beggining of the list" $ do
-                let data'' = Object $ HashMap.singleton "philosopher" Null
+                    Right actual <- either (pure . parseError) executeHero
-                    executionErrors = pure $ Error
+                        $ parse document "" "{ hero(id: \"1\") { friends { name } } }"
-                        { message = "Value completion error. Expected type !String, found: null."
+                    let Response _ errors' = actual
-                        , locations = [Location 1 26]
+                        Error _ _ path' = fromJust $ Seq.lookup 0 errors'
-                        , path = [Segment "philosopher", Segment "firstLanguage"]
+                        expected = [Segment "hero", Segment "friends", Index 0, Segment "name"]
-                        }
+                     in path' `shouldBe` expected
-                    expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ philosopher(id: \"1\") { firstLanguage } }"
-                in actual `shouldBe` expected
 
         context "Subscription" $
-            it "subscribes" $
+            it "subscribes" $ do
                 let data'' = Object
                         $ HashMap.singleton "newQuote"
                         $ Object
                         $ HashMap.singleton "quote"
                         $ String "Naturam expelles furca, tamen usque recurret."
                     expected = Response data'' mempty
-                    Right (Left stream) = either (pure . parseError) execute'
+                Left stream <- execute philosopherSchema Nothing (mempty :: HashMap Name Type.Value)
+                    $ fromRight (error "Parse error")
                     $ parse document "" "subscription { newQuote { quote } }"
-                    Right (Just actual) = runConduit $ stream .| await
+                Just actual <- runConduit $ stream .| await
-                in actual `shouldBe` expected
+                actual `shouldBe` expected

tests/Language/GraphQL/Validate/RulesSpec.hs

@@ -29,6 +29,7 @@ queryType = ObjectType "Query" Nothing [] $ HashMap.fromList
     [ ("dog", dogResolver)
     , ("cat", catResolver)
     , ("findDog", findDogResolver)
+    , ("findCats", findCatsResolver)
     ]
   where
     dogField = Field Nothing (Out.NamedObjectType dogType) mempty
@@ -39,6 +40,11 @@ queryType = ObjectType "Query" Nothing [] $ HashMap.fromList
     findDogResolver = ValueResolver findDogField $ pure Null
     catField = Field Nothing (Out.NamedObjectType catType) mempty
     catResolver = ValueResolver catField $ pure Null
+    findCatsArguments = HashMap.singleton "commands"
+        $ In.Argument Nothing (In.NonNullListType $ In.NonNullEnumType catCommandType)
+        $ Just $ List []
+    findCatsField = Field Nothing (Out.NonNullListType $ Out.NonNullObjectType catType) findCatsArguments
+    findCatsResolver = ValueResolver findCatsField $ pure $ List []
 
 catCommandType :: EnumType
 catCommandType = EnumType "CatCommand" Nothing $ HashMap.fromList
@@ -538,7 +544,7 @@ spec =
                         }
                  in validate queryString `shouldContain` [expected]
 
-        context "noUndefinedVariablesRule" $
+        context "noUndefinedVariablesRule" $ do
             it "rejects undefined variables" $
                 let queryString = [gql|
                   query variableIsNotDefinedUsedInSingleFragment {
@@ -560,7 +566,35 @@ spec =
                         }
                  in validate queryString `shouldBe` [expected]
 
-        context "noUnusedVariablesRule" $
+            it "gets variable location inside an input object" $
+                let queryString = [gql|
+                  query {
+                    findDog (complex: { name: $name }) {
+                      name
+                    }
+                  }
+                |]
+                    expected = Error
+                        { message = "Variable \"$name\" is not defined."
+                        , locations = [AST.Location 2 29]
+                        }
+                 in validate queryString `shouldBe` [expected]
+
+            it "gets variable location inside an array" $
+                let queryString = [gql|
+                  query {
+                    findCats (commands: [JUMP, $command]) {
+                      name
+                    }
+                  }
+                |]
+                    expected = Error
+                        { message = "Variable \"$command\" is not defined."
+                        , locations = [AST.Location 2 30]
+                        }
+                 in validate queryString `shouldBe` [expected]
+
+        context "noUnusedVariablesRule" $ do
             it "rejects unused variables" $
                 let queryString = [gql|
                   query variableUnused($atOtherHomes: Boolean) {
@@ -577,6 +611,16 @@ spec =
                         }
                  in validate queryString `shouldBe` [expected]
 
+            it "detects variables in properties of input objects" $
+                let queryString = [gql|
+                  query withVar ($name: String!) {
+                    findDog (complex: { name: $name }) {
+                      name
+                    }
+                  }
+                |]
+                 in validate queryString `shouldBe` []
+
         context "uniqueInputFieldNamesRule" $
             it "rejects duplicate fields in input objects" $
                 let queryString = [gql|
@@ -878,7 +922,7 @@ spec =
                         { message =
                             "Variable \"$dogCommandArg\" of type \
                             \\"DogCommand\" used in position expecting type \
-                            \\"!DogCommand\"."
+                            \\"DogCommand!\"."
                         , locations = [AST.Location 1 26]
                         }
                  in validate queryString `shouldBe` [expected]
@@ -925,7 +969,7 @@ spec =
                 |]
                     expected = Error
                         { message =
-                            "Value 3 cannot be coerced to type \"!CatCommand\"."
+                            "Value 3 cannot be coerced to type \"CatCommand!\"."
                         , locations = [AST.Location 3 36]
                         }
                  in validate queryString `shouldBe` [expected]
@@ -940,7 +984,7 @@ spec =
                 |]
                     expected = Error
                         { message =
-                            "Value 3 cannot be coerced to type \"!String\"."
+                            "Value 3 cannot be coerced to type \"String!\"."
                         , locations = [AST.Location 2 28]
                         }
                  in validate queryString `shouldBe` [expected]

tests/Schemas/HeroSchema.hs

@@ -0,0 +1,70 @@
+{- 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 Schemas.HeroSchema (heroSchema) where
+
+import Control.Exception (Exception(..))
+import Control.Monad.Catch (throwM)
+import Language.GraphQL.Error (ResolverException (..))
+import qualified Language.GraphQL.Type.In as In
+import qualified Language.GraphQL.Type as Type
+import Language.GraphQL.Type.Schema (schemaWithTypes)
+import qualified Data.HashMap.Strict as HashMap
+import Data.Typeable (cast)
+import qualified Language.GraphQL.Type.Out as Out
+
+data HeroException = HeroException
+    deriving Show
+
+instance Exception HeroException where
+    toException = toException. ResolverException
+    fromException e = do
+        ResolverException resolverException <- fromException e
+        cast resolverException
+
+heroSchema :: Type.Schema IO
+heroSchema =
+    schemaWithTypes Nothing queryType Nothing Nothing [] mempty
+
+type ObjectType = Out.ObjectType IO
+
+queryType :: ObjectType
+queryType = Out.ObjectType "Query" Nothing []
+    $ HashMap.fromList
+        [ ("hero", Out.ValueResolver heroField heroResolver)
+        ]
+  where
+    heroField = Out.Field Nothing (Out.NamedObjectType heroType)
+        $ HashMap.singleton "id"
+        $ In.Argument Nothing (In.NamedScalarType Type.id) Nothing
+    heroResolver = pure $ Type.Object mempty
+
+stringField :: Out.Field IO
+stringField = Out.Field Nothing (Out.NonNullScalarType Type.string) HashMap.empty
+
+heroType :: ObjectType
+heroType = Out.ObjectType "Hero" Nothing [] $ HashMap.fromList resolvers
+  where
+    resolvers =
+        [ ("id", Out.ValueResolver stringField (pure $ Type.String "4111"))
+        , ("name", Out.ValueResolver stringField (pure $ Type.String "R2D2"))
+        , ("friends", Out.ValueResolver friendsField (pure $ Type.List [luke]))
+        ]
+    friendsField = Out.Field Nothing (Out.ListType $ Out.NonNullObjectType lukeType) HashMap.empty
+    -- This list values are ignored because of current realisation (types and resolvers are the same entity)
+    -- The values from lukeType will be used
+    luke = Type.Object $ HashMap.fromList
+        [ ("id", "dfdfdf")
+        , ("name", "dfdfdff")
+        ]
+
+lukeType :: ObjectType
+lukeType = Out.ObjectType "Luke" Nothing [] $ HashMap.fromList resolvers
+  where
+    resolvers =
+        [ ("id", Out.ValueResolver stringField (pure $ Type.String "1000"))
+        , ("name", Out.ValueResolver stringField (throwM HeroException))
+        ]