Add a release task

Update QuickCheck and containers
Remove deprecated symbols from the Error module
2024-05-01 16:38:17 +02:00 · 2024-05-01 14:06:33 +02:00 · 2024-04-04 18:51:58 +02:00 · 2024-04-03 18:17:23 +02:00 · 2024-04-02 22:06:16 +02:00 · 2024-01-09 14:29:54 +01:00
26 changed files with 1183 additions and 504 deletions
--- a/.gitea/workflows/build.yml
+++ b/.gitea/workflows/build.yml
@ -0,0 +1,52 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - '**'
+  pull_request:
+    branches: [master]
+
+jobs:
+  audit:
+    runs-on: haskell
+    steps:
+      - name: Set up environment
+        run: |
+          apt-get update -y
+          apt-get upgrade -y
+          apt-get install -y nodejs pkg-config
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: |
+          cabal update
+          cabal install hlint "--constraint=hlint ==3.8"
+      - run: cabal exec hlint -- src tests
+
+  test:
+    runs-on: haskell
+    steps:
+      - name: Set up environment
+        run: |
+          apt-get update -y
+          apt-get upgrade -y
+          apt-get install -y nodejs pkg-config
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: cabal update
+      - name: Prepare system
+        run: cabal build graphql-test
+      - run: cabal test --test-show-details=streaming
+
+  doc:
+    runs-on: haskell
+    steps:
+      - name: Set up environment
+        run: |
+          apt-get update -y
+          apt-get upgrade -y
+          apt-get install -y nodejs pkg-config
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: cabal update
+      - run: cabal haddock --enable-documentation
--- a/.gitea/workflows/release.yml
+++ b/.gitea/workflows/release.yml
@ -0,0 +1,23 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - '**'
+
+jobs:
+  release:
+    runs-on: haskell
+    steps:
+      - name: Set up environment
+        run: |
+          apt-get update -y
+          apt-get upgrade -y
+          apt-get install -y nodejs pkg-config
+      - uses: actions/checkout@v4
+      - name: Upload a candidate
+        env:
+          HACKAGE_PASSWORD: ${{ secrets.HACKAGE_PASSWORD }}
+        run: |
+          cabal sdist
+          cabal upload --username belka --password ${HACKAGE_PASSWORD}
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -6,6 +6,65 @@ The format is based on
 and this project adheres to
 [Haskell Package Versioning Policy](https://pvp.haskell.org/).

+## [1.3.0.0] - 2024-05-01
+### Changed
+- Remove deprecated `runCollectErrs`, `Resolution`, `CollectErrsT` from the
+  `Error` module.
+
+## [1.2.0.3] - 2024-01-09
+### Fixed
+- Fix corrupted source distribution.
+
+## [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 +420,6 @@ 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 +524,28 @@ 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
-[1.0.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v1.0.1.0&rev_to=v1.0.0.0
-[1.0.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v1.0.0.0&rev_to=v0.11.1.0
-[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
-[0.11.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.11.0.0&rev_to=v0.10.0.0
-[0.10.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.10.0.0&rev_to=v0.9.0.0
-[0.9.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.9.0.0&rev_to=v0.8.0.0
-[0.8.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.8.0.0&rev_to=v0.7.0.0
-[0.7.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.7.0.0&rev_to=v0.6.1.0
-[0.6.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.6.1.0&rev_to=v0.6.0.0
-[0.6.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.6.0.0&rev_to=v0.5.1.0
-[0.5.1.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.5.1.0&rev_to=v0.5.0.1
-[0.5.0.1]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.5.0.1&rev_to=v0.5.0.0
-[0.5.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.5.0.0&rev_to=v0.4.0.0
-[0.4.0.0]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.4.0.0&rev_to=v0.3
-[0.3]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.3&rev_to=v0.2.1
-[0.2.1]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.2.1&rev_to=v0.2
-[0.2]: https://www.caraus.tech/projects/pub-graphql/repository/23/diff?rev=v0.2&rev_to=v0.1
+[1.3.0.0]: https://git.caraus.tech/OSS/graphql/compare/v1.2.0.3...v1.3.0.0
+[1.2.0.3]: https://git.caraus.tech/OSS/graphql/compare/v1.2.0.2...v1.2.0.3
+[1.2.0.2]: https://git.caraus.tech/OSS/graphql/compare/v1.2.0.1...v1.2.0.2
+[1.2.0.1]: https://git.caraus.tech/OSS/graphql/compare/v1.2.0.0...v1.2.0.1
+[1.2.0.0]: https://git.caraus.tech/OSS/graphql/compare/v1.1.0.0...v1.2.0.0
+[1.1.0.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.3.0...v1.1.0.0
+[1.0.3.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.2.0...v1.0.3.0
+[1.0.2.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.1.0...v1.0.2.0
+[1.0.1.0]: https://git.caraus.tech/OSS/graphql/compare/v1.0.0.0...v1.0.1.0
+[1.0.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.11.1.0...v1.0.0.0
+[0.11.1.0]: https://git.caraus.tech/OSS/graphql/compare/v0.11.0.0...v0.11.1.0
+[0.11.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.10.0.0...v0.11.0.0
+[0.10.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.9.0.0...v0.10.0.0
+[0.9.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.8.0.0...v0.9.0.0
+[0.8.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.7.0.0...v0.8.0.0
+[0.7.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.6.1.0...v0.7.0.0
+[0.6.1.0]: https://git.caraus.tech/OSS/graphql/compare/v0.6.0.0...v0.6.1.0
+[0.6.0.0]: https://git.caraus.tech/OSS/graphql/compare/v0.5.1.0...v0.6.0.0
+[0.5.1.0]: https://git.caraus.tech/OSS/graphql/compare/v0.5.0.1...v0.5.1.0
+[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
--- a/README.md
+++ b/README.md
@ -1,15 +1,12 @@
 # GraphQL implementation in Haskell

-[![Simple Haskell](https://www.simplehaskell.org/badges/badge.svg)](https://www.simplehaskell.org)
-[![CI/CD](https://img.shields.io/badge/CI-CD-brightgreen)](https://build.caraus.tech/go/pipelines)
-
-See https://www.caraus.tech/projects/pub-graphql.
+See https://git.caraus.tech/OSS/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).
--- a/graphql.cabal
+++ b/graphql.cabal
@ -1,17 +1,17 @@
 cabal-version: 2.4

 name:           graphql
-version:        1.0.2.0
+version:        1.3.0.0
 synopsis:       Haskell GraphQL implementation
 description:    Haskell <https://spec.graphql.org/June2018/ GraphQL> implementation.
 category:       Language
-homepage:       https://www.caraus.tech/projects/pub-graphql
-bug-reports:    https://www.caraus.tech/projects/pub-graphql/issues
+homepage:       https://git.caraus.tech/OSS/graphql
+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 == 9.0.1,
-  GHC == 9.2.1
+  GHC == 9.4.7,
+  GHC == 9.6.3

 source-repository head
  type: git
-  location: git://caraus.tech/pub/graphql.git
-
-flag Json
-  description: Whether to build against @aeson 1.x@
-  default: True
-  manual: True
+  location: https://git.caraus.tech/OSS/graphql.git

 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
@ -67,21 +60,15 @@ library
  build-depends:
    base >= 4.7 && < 5,
    conduit ^>= 1.3.4,
-    containers ^>= 0.6.2,
+    containers >= 0.6 && < 0.8,
    exceptions ^>= 0.10.4,
    megaparsec >= 9.0 && < 10,
    parser-combinators >= 1.3 && < 2,
    template-haskell >= 2.16 && < 3,
-    text ^>= 1.2.4,
-    transformers ^>= 0.5.6,
+    text >= 1.2 && < 3,
+    transformers >= 0.5.6 && < 0.7,
    unordered-containers ^>= 0.2.14,
-    vector ^>= 0.12.3
-  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
+    vector >= 0.12 && < 0.14

  default-language: Haskell2010

@ -93,25 +80,32 @@ 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

  build-depends:
-    QuickCheck ^>= 2.14.1,
+    QuickCheck >= 2.14 && < 2.16,
    base,
    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
--- a/src/Language/GraphQL.hs
+++ b/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 qualified Data.Aeson.Types as Aeson
-import qualified Data.HashMap.Strict as HashMap
-import Data.Maybe (catMaybes)
+import Data.HashMap.Strict (HashMap)
 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.
-    -> Text -- ^ Text representing a @GraphQL@ request document.
-    -> 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
+--
+-- An operation name can be given if the document contains multiple operations.
+graphql :: (MonadCatch m, VariableValue a, Serialize b)
    => 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.
-graphqlSubs schema operationName variableValues document' =
-    case parse document "" document' of
-        Left errorBundle -> pure . formatResponse <$> parseError errorBundle
+    -> m (Either (ResponseEventStream m b) (Response b)) -- ^ Response.
+graphql schema operationName variableValues document' =
+    case parse Full.document "" document' of
+        Left errorBundle -> pure  <$> parseError errorBundle
        Right parsed ->
            case validate parsed of
-                Seq.Empty -> fmap formatResponse
-                    <$> execute schema operationName variableValues parsed
+                Seq.Empty -> execute schema operationName variableValues parsed
                errors -> pure $ pure
-                    $ HashMap.singleton "errors"
-                    $ Aeson.toJSON
+                    $ Response null
                    $ fromValidationError <$> errors
  where
    validate = Validate.document schema Validate.specifiedRules
-    formatResponse (Response data'' Seq.Empty) = HashMap.singleton "data" data''
-    formatResponse (Response data'' errors') = HashMap.fromList
-        [ ("data", data'')
-        , ("errors", Aeson.toJSON $ fromError <$> errors')
-        ]
-    fromError Error{..} = Aeson.object $ catMaybes
-        [ Just ("message", Aeson.toJSON message)
-        , toMaybe fromLocation "locations" locations
-        , toMaybe fromPath "path" path
-        ]
-    fromValidationError Validate.Error{..} = Aeson.object
-        [ ("message", Aeson.toJSON message)
-        , ("locations", Aeson.listValue fromLocation locations)
-        ]
-    toMaybe _ _ [] = Nothing
-    toMaybe f key xs = Just (key, Aeson.listValue f xs)
-    fromPath (Segment segment) = Aeson.String segment
-    fromPath (Index index) = Aeson.toJSON index
-    fromLocation Location{..} = Aeson.object
-        [ ("line", Aeson.toJSON line)
-        , ("column", Aeson.toJSON column)
-        ]
-#else
-- | This module provides the functions to parse and execute @GraphQL@ queries.
-module Language.GraphQL
-    (
-    ) where
-#endif
+    fromValidationError Validate.Error{..} = Error
+        { message = Text.pack message
+        , locations = locations
+        , path = []
+        }
--- a/src/Language/GraphQL/AST/Document.hs
+++ b/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 (NonNullTypeList listType) =  concat ["![", show listType, "]"]
+    show (NonNullTypeNamed typeName) = Text.unpack $ typeName <> "!"
+    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.
--- a/src/Language/GraphQL/AST/Encoder.hs
+++ b/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
-    incrementIndent
-        | Pretty indentation <- formatter = Pretty $ indentation + 1
-        | otherwise = Minified
-    indent'
-        | Pretty indentation <- formatter = indent $ indentation + 1
-        | otherwise = ""
+        fragmentSpread formatter' fragmentSelection
+    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

 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 formatter = Lazy.Text.cons ' ' . spaces (directive formatter)
+directives Minified values = spaces (directive Minified) values
+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
--- a/src/Language/GraphQL/AST/Lexer.hs
+++ b/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
--- a/src/Language/GraphQL/AST/Parser.hs
+++ b/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.Object <$> braces (some $ objectField $ valueNode value)
+    <|> Full.List <$> brackets (many $ valueNode value)
+    <|> Full.Object <$> braces (many $ objectField $ valueNode value)
    <?> "Value"

 constValue :: Parser Full.ConstValue
--- a/src/Language/GraphQL/Error.hs
+++ b/src/Language/GraphQL/Error.hs
@ -8,31 +8,22 @@

 -- | Error handling.
 module Language.GraphQL.Error
-    ( CollectErrsT
-    , Error(..)
+    ( Error(..)
    , Path(..)
-    , Resolution(..)
    , ResolverException(..)
    , Response(..)
    , ResponseEventStream
-    , addErr
-    , addErrMsg
    , parseError
-    , runCollectErrs
-    , singleError
    ) where

 import Conduit
 import Control.Exception (Exception(..))
-import Control.Monad.Trans.State (StateT, modify, runStateT)
-import Data.HashMap.Strict (HashMap)
 import Data.Sequence (Seq(..), (|>))
 import qualified Data.Sequence as Seq
 import Data.Text (Text)
 import qualified Data.Text as Text
-import Language.GraphQL.AST (Location(..), Name)
+import Language.GraphQL.AST (Location(..))
 import Language.GraphQL.Execute.Coerce
-import qualified Language.GraphQL.Type.Schema as Schema
 import Prelude hiding (null)
 import Text.Megaparsec
    ( ParseErrorBundle(..)
@ -100,57 +91,3 @@ instance Show ResolverException where
    show (ResolverException e) = show e

 instance Exception ResolverException
-
-- * Deprecated
-
-- | 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
-    -> m (Response a)
-runCollectErrs types' res = do
-    (dat, Resolution{..}) <- runStateT res
-        $ Resolution{ errors = Seq.empty, types = types' }
-    pure $ Response dat errors
-
-- | 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)
-    }
-
-- | 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
--- a/src/Language/GraphQL/Execute.hs
+++ b/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
-            [ "Operation \""
-            , Text.pack operationName
-            , "\" not found."
+    let queryErrorMessage = Text.unlines
+            [ Text.concat
+              [ "Operation \""
+              , Text.pack operationName
+              , "\" 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 \""
-            , variableName
-            , "\"."
+            [ "Failed to coerce the variable "
+            , 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 \""
-            , variableName
-            , "\" has unknown type \""
+            [ "Variable "
+            , Text.pack $ showVariableName variableDefinition
+            , " 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
-            newError = constructError e errorLocation newPath
+        let newError = constructError e errorLocation fieldErrorPath
         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
-        let updatedPath = Index index : errorPath
-        completedValue <- completeValue listType fields updatedPath listItem
-        pure (index + 1, completedValue : accumulator)
+    go accumulator listItem =
+        let updatedPath = Index (Vector.length accumulator) : errorPath
+         in Vector.snoc 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
-    $ fieldsSegment fields : errorPath
+    = executeSelectionSet (mergeSelectionSets fields) objectType result 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 <$> argumentValues
-    coerceArgumentValue inputType (Transform.Int integer) =
-        coerceInputLiteral inputType (Type.Int integer)
-    coerceArgumentValue inputType (Transform.Boolean boolean) =
-        coerceInputLiteral inputType (Type.Boolean boolean)
-    coerceArgumentValue inputType (Transform.String string) =
-        coerceInputLiteral inputType (Type.String string)
-    coerceArgumentValue inputType (Transform.Float float) =
-        coerceInputLiteral inputType (Type.Float float)
-    coerceArgumentValue inputType (Transform.Enum enum) =
-        coerceInputLiteral inputType (Type.Enum enum)
-    coerceArgumentValue inputType Transform.Null
-        | In.isNonNullType inputType = Nothing
-        | otherwise = coerceInputLiteral inputType Type.Null
-    coerceArgumentValue (In.ListBaseType inputType) (Transform.List list) =
-        let coerceItem = coerceArgumentValue inputType
-         in Type.List <$> traverse coerceItem list
-    coerceArgumentValue (In.InputObjectBaseType inputType) (Transform.Object object)
-        | In.InputObjectType _ _ inputFields <- inputType = 
-            let go = forEachField object
-                resultMap = HashMap.foldrWithKey go (pure mempty) inputFields
-             in Type.Object <$> resultMap
-    coerceArgumentValue _ (Transform.Variable variable) = pure variable
-    coerceArgumentValue _ _ = Nothing
-    forEachField object variableName (In.InputField _ variableType defaultValue) =
-        matchFieldValues coerceArgumentValue object variableName variableType defaultValue
+
+    coerceArgumentValue inputType transform =
+      coerceInputLiteral inputType $ extractArgumentValue transform
+
+    extractArgumentValue (Transform.Int integer) = Type.Int integer
+    extractArgumentValue (Transform.Boolean boolean) = Type.Boolean boolean
+    extractArgumentValue (Transform.String string) = Type.String string
+    extractArgumentValue (Transform.Float float) = Type.Float float
+    extractArgumentValue (Transform.Enum enum) = Type.Enum enum
+    extractArgumentValue Transform.Null = Type.Null
+    extractArgumentValue (Transform.List list) =
+      Type.List $ extractArgumentValue <$> list
+    extractArgumentValue (Transform.Object object) =
+      Type.Object $ extractArgumentValue <$> object
+    extractArgumentValue (Transform.Variable variable) = variable

 collectFields :: Monad m
    => Out.ObjectType m
--- a/src/Language/GraphQL/Execute/Coerce.hs
+++ b/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
--- a/src/Language/GraphQL/TH.hs
+++ b/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
--- a/src/Language/GraphQL/Type/Definition.hs
+++ b/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, "]!"]
--- a/src/Language/GraphQL/Type/In.hs
+++ b/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 (NonNullEnumType enumType) = '!' : show enumType
-    show (NonNullInputObjectType inputObjectType) = '!' : show inputObjectType
-    show (NonNullListType baseType) = concat ["![", show baseType, "]"]
+    show (NonNullScalarType scalarType) = Definition.showNonNullType scalarType
+    show (NonNullEnumType enumType) = Definition.showNonNullType enumType
+    show (NonNullInputObjectType inputObjectType) =
+        Definition.showNonNullType inputObjectType
+    show (NonNullListType baseType) = Definition.showNonNullListType baseType

 -- | Field argument definition.
 data Argument = Argument (Maybe Text) Type (Maybe Definition.Value)
--- a/src/Language/GraphQL/Type/Out.hs
+++ b/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 (NonNullEnumType enumType) = '!' : show enumType
-    show (NonNullObjectType inputObjectType) = '!' : show inputObjectType
-    show (NonNullInterfaceType interfaceType) = '!' : show interfaceType
-    show (NonNullUnionType unionType) = '!' : show unionType
-    show (NonNullListType baseType) = concat ["![", show baseType, "]"]
+    show (NonNullScalarType scalarType) = showNonNullType scalarType
+    show (NonNullEnumType enumType) = showNonNullType enumType
+    show (NonNullObjectType inputObjectType) = showNonNullType inputObjectType
+    show (NonNullInterfaceType interfaceType) = showNonNullType interfaceType
+    show (NonNullUnionType unionType) = showNonNullType unionType
+    show (NonNullListType baseType) = showNonNullListType baseType

 -- | Matches either 'NamedScalarType' or 'NonNullScalarType'.
 pattern ScalarBaseType :: forall m. ScalarType -> Type m
--- a/src/Language/GraphQL/Validate/Rules.hs
+++ b/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 _ = Nothing
+
+    findArgumentVariables (Full.Argument _ value _) = findNodeVariables value
+    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
--- a/src/Test/Hspec/GraphQL.hs
+++ b/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
--- a/tests/Language/GraphQL/AST/Arbitrary.hs
+++ b/tests/Language/GraphQL/AST/Arbitrary.hs
@ -0,0 +1,102 @@
+{-# 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)
+import Data.Functor ((<&>))
+
+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 =
+        let variableGen :: Gen Doc.Value
+            variableGen = Doc.Variable . getAnyName <$> arbitrary
+            listGen :: Gen [Doc.Node Doc.Value]
+            listGen = (resize 5 . listOf) nodeGen
+            nodeGen :: Gen (Doc.Node Doc.Value)
+            nodeGen = fmap getAnyNode arbitrary <&> fmap getAnyValue
+            objectGen :: Gen [Doc.ObjectField Doc.Value]
+            objectGen = resize 1
+                $ fmap getNonEmpty arbitrary
+                <&> map (fmap getAnyValue . getAnyObjectField)
+         in 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 <$> objectGen
+            ]
+
+newtype AnyArgument a = AnyArgument { getAnyArgument :: Doc.Argument }
+    deriving (Eq, Show)
+
+instance Arbitrary a => Arbitrary (AnyArgument a) where
+    arbitrary = do
+        name' <- getAnyName <$> 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'
--- a/tests/Language/GraphQL/AST/DocumentSpec.hs
+++ b/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
--- a/tests/Language/GraphQL/AST/EncoderSpec.hs
+++ b/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
--- a/tests/Language/GraphQL/AST/ParserSpec.hs
+++ b/tests/Language/GraphQL/AST/ParserSpec.hs
@ -5,46 +5,78 @@ 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}"

-    it "accepts block strings as argument" $
-        parse document "" `shouldSucceedOn` [gql|{
-              hello(text: """Argument""")
-            }|]
+    context "Arguments" $ do
+       it "accepts block strings as argument" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 hello(text: """Argument""")
+               }|]

-    it "accepts strings as argument" $
-        parse document "" `shouldSucceedOn` [gql|{
-              hello(text: "Argument")
-            }|]
+       it "accepts strings as argument" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 hello(text: "Argument")
+               }|]

-    it "accepts two required arguments" $
-        parse document "" `shouldSucceedOn` [gql|
-            mutation auth($username: String!, $password: String!){
-              test
-            }|]
+       it "accepts int as argument1" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 user(id: 4)
+               }|]

-    it "accepts two string arguments" $
-        parse document "" `shouldSucceedOn` [gql|
-            mutation auth{
-              test(username: "username", password: "password")
-            }|]
+       it "accepts boolean as argument" $
+           parse document "" `shouldSucceedOn` [gql|{
+                 hello(flag: true) { field1 }
+               }|]

-    it "accepts two block string arguments" $
-        parse document "" `shouldSucceedOn` [gql|
-            mutation auth{
-              test(username: """username""", password: """password""")
-            }|]
+       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!){
+                 test
+               }|]
+
+       it "accepts two string arguments" $
+           parse document "" `shouldSucceedOn` [gql|
+               mutation auth{
+                 test(username: "username", password: "password")
+               }|]
+
+       it "accepts two block string arguments" $
+           parse document "" `shouldSucceedOn` [gql|
+               mutation auth{
+                 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|
            """
--- a/tests/Language/GraphQL/ExecuteSpec.hs
+++ b/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)
-    genresResolver = throwM PhilosopherException
+    throwingResolver :: Resolve IO
+    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)
-    (Response Value)
+    (ResponseEventStream IO Type.Value)
+    (Response Type.Value)

-execute' :: Document -> Either SomeException EitherStreamOrValue
-execute' =
-    execute philosopherSchema Nothing (mempty :: HashMap Name Value)
+-- Asserts that a query resolves to a value.
+shouldResolveTo :: Text.Text -> Response Type.Value -> Expectation
+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'
-                    $ parse document "" sourceQuery
-             in actual `shouldBe` expected
+             in sourceQuery `shouldResolveTo` 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'
-                        $ parse document "" "{ philosopher { firstName surname } }"
-                in actual `shouldBe` expected
+                    sourceQuery = "{ philosopher { firstName surname } }"
+                in sourceQuery `shouldResolveTo` expected
            it "merges selections" $
                let data'' = Object
                        $ HashMap.singleton "philosopher"
@ -231,119 +300,174 @@ spec =
                            , ("lastName", String "Nietzsche")
                            ]
                    expected = Response data'' mempty
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ philosopher { firstName } philosopher { lastName } }"
-                in actual `shouldBe` expected
+                    sourceQuery = "{ philosopher { firstName } philosopher { lastName } }"
+                in sourceQuery `shouldResolveTo` 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'
-                        $ parse document "" "{ philosopher { school } }"
-                in actual `shouldBe` expected
+                    sourceQuery = "{ philosopher { school } }"
+                 in sourceQuery `shouldResolveTo` 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'
-                        $ parse document "" "{ philosopher { interest } }"
-                in actual `shouldBe` expected
+                    sourceQuery = "{ philosopher { interest } }"
+                 in sourceQuery `shouldResolveTo` 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'
-                        $ parse document "" "{ philosopher { majorWork { title } } }"
-                in actual `shouldBe` expected
-
-            it "gives location information for invalid scalar arguments" $
-                let data'' = Object $ HashMap.singleton "philosopher" Null
-                    executionErrors = pure $ Error
-                        { message =
-                            "Argument \"id\" has invalid type. Expected type ID, found: True."
-                        , locations = [Location 1 15]
-                        , path = [Segment "philosopher"]
-                        }
-                    expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ philosopher(id: true) { lastName } }"
-                in actual `shouldBe` expected
+                    sourceQuery = "{ philosopher { majorWork { title } } }"
+                 in sourceQuery `shouldResolveTo` 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."
+                        { message = "Unable to coerce result to Int!."
                        , locations = [Location 1 26]
                        , path = [Segment "philosopher", Segment "century"]
                        }
                    expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ philosopher(id: \"1\") { century } }"
-                in actual `shouldBe` expected
+                    sourceQuery = "{ philosopher(id: \"1\") { century } }"
+                in sourceQuery `shouldResolveTo` expected

            it "gives location information for failed result coercion" $
-                let data'' = Object $ HashMap.singleton "genres" Null
+                let data'' = Object $ HashMap.singleton "throwing" Null
                    executionErrors = pure $ Error
                        { message = "PhilosopherException"
                        , locations = [Location 1 3]
-                        , path = [Segment "genres"]
+                        , path = [Segment "throwing"]
                        }
                    expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ genres }"
-                in actual `shouldBe` expected
+                    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."
+                        { message = "Unable to coerce result to Int!."
                        , 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
+                    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."
+                        { message = "Value completion error. Expected type String!, found: null."
                        , locations = [Location 1 26]
                        , path = [Segment "philosopher", Segment "firstLanguage"]
                        }
                    expected = Response data'' executionErrors
-                    Right (Right actual) = either (pure . parseError) execute'
-                        $ parse document "" "{ philosopher(id: \"1\") { firstLanguage } }"
-                in actual `shouldBe` expected
+                    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
+                            { message =
+                                "Argument \"id\" has invalid type. Expected type ID, found: True."
+                            , locations = [Location 1 15]
+                            , path = [Segment "philosopher"]
+                            }
+                        expected = Response data'' executionErrors
+                        sourceQuery = "{ philosopher(id: true) { lastName } }"
+                    in sourceQuery `shouldResolveTo` expected
+
+                it "puts an object in a list if needed" $
+                    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 = "Failed to coerce the variable $id: String."
+                            , locations =[Location 1 7]
+                            , path = []
+                            }
+                        expected = Response data'' executionErrors
+                        executeWithVars = execute philosopherSchema Nothing (HashMap.singleton "id" (Type.Int 1))
+                    Right actual <- either (pure . parseError) executeWithVars
+                        $ parse document "" "query($id: String) { philosopher(id: \"1\") { firstLanguage } }"
+                    actual `shouldBe` expected
+
+                it "throws variable unkown input type error" $
+                    let data'' = Null
+                        executionErrors = pure $ Error
+                            { message = "Variable $id has unknown type Cat."
+                            , locations =[Location 1 7]
+                            , path = []
+                            }
+                        expected = Response data'' executionErrors
+                        sourceQuery = "query($id: Cat) { philosopher(id: \"1\") { firstLanguage } }"
+                     in sourceQuery `shouldResolveTo` expected
+
+            context "Error path" $ do
+                let executeHero :: Document -> IO EitherStreamOrValue
+                    executeHero = execute heroSchema Nothing (HashMap.empty :: HashMap Name Type.Value)
+
+                it "at the beggining of the list" $ do
+                    Right actual <- either (pure . parseError) executeHero
+                        $ parse document "" "{ hero(id: \"1\") { friends { name } } }"
+                    let Response _ errors' = actual
+                        Error _ _ path' = fromJust $ Seq.lookup 0 errors'
+                        expected = [Segment "hero", Segment "friends", Index 0, Segment "name"]
+                     in path' `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'
-                        $ parse document "" "subscription { newQuote { quote } }"
-                    Right (Just actual) = runConduit $ stream .| await
-                in actual `shouldBe` expected
+                Left stream <- execute philosopherSchema Nothing (mempty :: HashMap Name Type.Value)
+                    $ fromRight (error "Parse error")
+                    $ parse document "" "subscription { newQuote { quote } }"
+                Just actual <- runConduit $ stream .| await
+                actual `shouldBe` expected
--- a/tests/Language/GraphQL/Validate/RulesSpec.hs
+++ b/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]
--- a/tests/Schemas/HeroSchema.hs
+++ b/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))
+        ]
Author	SHA1	Message	Date
Eugen Wissner	1c4584abdd	Add a release task Some checks failed Build / audit (push) Successful in 13m31s Details Build / test (push) Successful in 6m11s Details Build / doc (push) Successful in 5m23s Details Release / release (push) Failing after 16s Details	2024-05-01 16:38:17 +02:00
Eugen Wissner	e071553e75	Update QuickCheck and containers All checks were successful Build / audit (push) Successful in 13m26s Details Build / test (push) Successful in 6m12s Details Build / doc (push) Successful in 5m17s Details	2024-05-01 14:06:33 +02:00
Eugen Wissner	e731c7db07	Remove deprecated symbols from the Error module All checks were successful Build / audit (push) Successful in 14m21s Details Build / test (push) Successful in 6m22s Details Build / doc (push) Successful in 5m33s Details	2024-04-04 18:51:58 +02:00
Eugen Wissner	303cf18d77	Switch to haskell images in the CI All checks were successful Build / audit (push) Successful in 13m52s Details Build / test (push) Successful in 6m12s Details Build / doc (push) Successful in 5m18s Details	2024-04-03 18:17:23 +02:00
Eugen Wissner	6b8346e527	Update hlint to 3.8 All checks were successful Build / audit (push) Successful in 13m37s Details Build / test (push) Successful in 6m16s Details Build / doc (push) Successful in 6m20s Details	2024-04-02 22:06:16 +02:00
Eugen Wissner	303f84ed41	Release 1.2.0.3 All checks were successful Build / audit (push) Successful in 15m3s Details Build / test (push) Successful in 8m10s Details Build / doc (push) Successful in 6m52s Details	2024-01-09 14:29:54 +01:00
Eugen Wissner	d2ea9fb467	Release 1.2.0.2 All checks were successful Build / audit (push) Successful in 15m2s Details Build / test (push) Successful in 8m0s Details Build / doc (push) Successful in 6m51s Details	2024-01-08 22:29:58 +01:00
Eugen Wissner	809f446ff1	Fix variable location in objects and lists All checks were successful Build / audit (push) Successful in 15m35s Details Build / test (push) Successful in 8m6s Details Build / doc (push) Successful in 6m59s Details	2024-01-05 20:46:02 +01:00
Eugen Wissner	b1b6bfcdb9	Add a test for the wrong variable location All checks were successful Build / audit (push) Successful in 16m30s Details Build / test (push) Successful in 8m26s Details Build / doc (push) Successful in 7m6s Details inside an input object for the role checking for unused and undefined variables.	2023-12-28 09:45:39 +01:00
Matei Adriel	59aa010f0b	Fix "variable is not used" error All checks were successful Build / audit (pull_request) Successful in 16m24s Details Build / test (pull_request) Successful in 9m2s Details Build / doc (pull_request) Successful in 7m22s Details Build / audit (push) Successful in 16m16s Details Build / test (push) Successful in 8m29s Details Build / doc (push) Successful in 7m36s Details	2023-12-27 12:50:17 +01:00
Eugen Wissner	b1c5a568dd	Add a failing test for unused variables bug All checks were successful Build / audit (push) Successful in 15m27s Details Build / test (push) Successful in 8m32s Details Build / doc (push) Successful in 7m24s Details	2023-12-21 21:34:37 +01:00
Eugen Wissner	5ffe8c72fa	Add a workflow All checks were successful Build / audit (push) Successful in 16m26s Details Build / test (push) Successful in 7m51s Details Build / doc (push) Successful in 6m26s Details	2023-11-27 13:00:55 +01:00
Eugen Wissner	a961b168db	Add a test for the input object coercion issue	2023-11-08 20:08:47 +01:00
Matei Adriel	a1cda38e20	Fix values not being coerced to lists	2023-11-04 13:46:10 +01:00
Eugen Wissner	7c78497e04	Add a CHANGELOG entry for the show type fix	2023-10-14 16:40:19 +02:00
Eugen Wissner	fdc43e4e25	Fix non nullable type representation …in executor error messages.	2023-10-13 20:42:24 +02:00
Eugen Wissner	2fdf04f54a	Remove leading carriage return in gql	2023-08-03 08:00:36 +02:00
Eugen Wissner	3ed7dcd401	Support hspec 2.11	2023-04-25 08:51:18 +02:00
Eugen Wissner	408dfb4301	Update web links All checks were successful test Test.	2023-03-23 09:46:04 +01:00
Eugen Wissner	3b69dac371	Release 1.2.0.0 All checks were successful test Test.	2023-02-28 17:54:02 +01:00
Eugen Wissner	2834360411	Remove JSON support in the core package	2023-02-26 09:43:43 +01:00
Eugen Wissner	83f2dc1a2d	Encode type extensions	2023-02-25 10:15:22 +01:00
Eugen Wissner	3b0da4f3d7	Fix resolvers returning a list in the reverse order	2023-02-24 17:14:43 +01:00
Eugen Wissner	d83f75b341	Encode schema extensions	2023-01-26 06:47:44 +01:00
Eugen Wissner	85d876e131	Update the 2023 copyright	2023-01-12 13:02:50 +01:00
Eugen Wissner	05fa5df558	Encode directive definitions	2023-01-11 10:28:45 +01:00
Eugen Wissner	9021f3a25d	Encode input object types	2023-01-10 09:53:18 +01:00
Eugen Wissner	025331a9ee	Encode enums	2023-01-09 20:56:21 +01:00
Eugen Wissner	ab4808c44d	Encode unions	2023-01-08 17:33:25 +01:00
Eugen Wissner	bb4375313e	Encode object type definitions	2023-01-03 13:10:33 +01:00
Eugen Wissner	70dedb6911	Encode interfaces (2018)	2023-01-02 10:30:37 +01:00
Eugen Wissner	a96d4e6ef3	Add Semigroup and Monoid instances for Description	2022-12-27 10:38:08 +01:00
Eugen Wissner	3ce6e7da46	Encode schema definitions	2022-12-25 16:38:00 +01:00
Eugen Wissner	a5cf0a32e8	Replace ">> pure ()" with void	2022-12-24 18:59:40 +01:00
Eugen Wissner	2f9881bb21	Fix GHC 9.2 warnings and deprecations - Fix GHC 9.2 warnings - Convert comments to proper deprecations	2022-12-24 18:09:52 +01:00
Eugen Wissner	bf2e4925b4	Add operation type encoder	2022-10-02 11:38:53 +02:00
Eugen Wissner	2321d1a1bc	Eliminate non-exhaustive patterns in ExecuteSpec	2022-07-02 15:29:35 +02:00
Eugen Wissner	2f19093803	Change execute' to shouldResolveTo helper method	2022-07-01 12:18:02 +02:00
Eugen Wissner	0dac9701bc	Document usage of the json flag	2022-06-30 11:10:46 +02:00
Eugen Wissner	0d25f482dd	Remove deprecated Error functions	2022-03-31 21:49:44 +02:00
Eugen Wissner	a2401d563b	Allow version 2.0 of the text package.	2022-03-27 13:41:16 +02:00
Dmitrii Skurikhin	8503c0f288	enhance query errors	2022-02-16 08:58:16 +01:00
Dmitrii Skurikhin	05e6aa4c95	add Arbitrary instances for AST.Document, add random arguments Parser test	2022-02-14 19:18:13 +01:00
Eugen Wissner	647547206f	Add back graphql function, but jsonless	2022-01-20 11:43:21 +01:00
Dmitrii Skurikhin	0c8edae90a	fix empty list argument parsing	2022-01-09 09:00:56 +01:00
Eugen Wissner	73585dde85	Add unreleased changelog entry	2022-01-07 08:45:34 +01:00
Dmitrii Skurikhin	1f7bd92d11	fix index position in error path	2022-01-07 08:31:47 +01:00