Release 1.0.1.0

CHANGELOG.md

@@ -6,7 +6,23 @@ The format is based on
 and this project adheres to
 [Haskell Package Versioning Policy](https://pvp.haskell.org/).
 
-## [1.0.0.0]
+## [1.0.1.0] - 2021-09-27
+### Added
+- Custom `Show` instance for `Type.Definition.Value` (for error
+  messages).
+- Path information in errors (path to the field throwing the error).
+- Deprecation notes in the `Error` module for `Resolution`, `CollectErrsT` and
+  `runCollectErrs`. These symbols are part of the old executor and aren't used
+  anymore, it will be deprecated in the future and removed.
+- `TH` module with the `gql` quasi quoter.
+
+### Fixed
+- Error messages are more concrete, they also contain type information and
+  wrong values, where appropriate and possible.
+- If the field with an error is Non-Nullable, the error is propagated to the
+  first nullable field, as required by the specification.
+
+## [1.0.0.0] - 2021-07-04
 ### Added
 - `Language.GraphQL.Execute.OrderedMap` is a map data structure, that preserves
   insertion order.
@@ -443,6 +459,7 @@ and this project adheres to
 ### Added
 - Data types for the GraphQL language.
 
+[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

graphql.cabal

@@ -1,7 +1,7 @@
 cabal-version: 2.2
 
 name:           graphql
-version:        1.0.0.0
+version:        1.0.1.0
 synopsis:       Haskell GraphQL implementation
 description:    Haskell <https://spec.graphql.org/June2018/ GraphQL> implementation.
 category:       Language
@@ -20,7 +20,9 @@ build-type:     Simple
 extra-source-files:
     CHANGELOG.md
     README.md
-tested-with: GHC == 8.10.4
+tested-with:
+    GHC == 8.10.7
+  , GHC == 9.0.1
 
 source-repository head
   type: git
@@ -39,6 +41,7 @@ library
       Language.GraphQL.Execute
       Language.GraphQL.Execute.Coerce
       Language.GraphQL.Execute.OrderedMap
+      Language.GraphQL.TH
       Language.GraphQL.Type
       Language.GraphQL.Type.In
       Language.GraphQL.Type.Out
@@ -47,9 +50,6 @@ library
       Language.GraphQL.Validate.Validation
       Test.Hspec.GraphQL
   other-modules:
-      Language.GraphQL.Execute.Execution
-      Language.GraphQL.Execute.Internal
-      Language.GraphQL.Execute.Subscribe
       Language.GraphQL.Execute.Transform
       Language.GraphQL.Type.Definition
       Language.GraphQL.Type.Internal
@@ -67,6 +67,7 @@ library
     , megaparsec >= 9.0.1 && < 9.1
     , parser-combinators >= 1.3.0 && < 1.4
     , scientific >= 0.3.7 && < 0.4
+    , template-haskell >= 2.16 && < 2.18
     , text >= 1.2.4 && < 1.3
     , transformers >= 0.5.6 && < 0.6
     , unordered-containers >= 0.2.14 && < 0.3
@@ -96,14 +97,13 @@ test-suite graphql-test
   build-depends:
       QuickCheck >= 2.14.1 && < 2.15
     , aeson
-    , base >= 4.7 && < 5
+    , base >= 4.8 && < 5
     , conduit
     , exceptions
     , graphql
     , hspec >= 2.8.2 && < 2.9
     , hspec-megaparsec >= 2.2.0 && < 2.3
     , megaparsec
-    , raw-strings-qq >= 1.1 && < 1.2
     , scientific
     , text
     , unordered-containers

src/Language/GraphQL/AST.hs

@@ -1,6 +1,4 @@
-{- This Source Code Form is subject to the terms of the Mozilla Public License,
-   v. 2.0. If a copy of the MPL was not distributed with this file, You can
-   obtain one at https://mozilla.org/MPL/2.0/. -}
+{-# LANGUAGE Safe #-}
 
 -- | Target AST for parser.
 module Language.GraphQL.AST

src/Language/GraphQL/AST/DirectiveLocation.hs

@@ -1,7 +1,3 @@
-{- This Source Code Form is subject to the terms of the Mozilla Public License,
-   v. 2.0. If a copy of the MPL was not distributed with this file, You can
-   obtain one at https://mozilla.org/MPL/2.0/. -}
-
 {-# LANGUAGE Safe #-}
 
 -- | Various parts of a GraphQL document can be annotated with directives. 

src/Language/GraphQL/Error.hs

@@ -1,3 +1,7 @@
+{- 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 DuplicateRecordFields #-}
 {-# LANGUAGE ExistentialQuantification #-}
 {-# LANGUAGE RecordWildCards #-}
@@ -40,12 +44,6 @@ import Text.Megaparsec
     , unPos
     )
 
--- | Executor context.
-data Resolution m = Resolution
-    { errors :: Seq Error
-    , types :: HashMap Name (Schema.Type m)
-    }
-
 -- | Wraps a parse error into a list of errors.
 parseError :: (Applicative f, Serialize a)
     => ParseErrorBundle Text Void
@@ -65,32 +63,6 @@ parseError ParseErrorBundle{..}  =
             sourcePosition = pstateSourcePos newState
          in (result |> errorObject x sourcePosition, newState)
 
--- | A wrapper to pass error messages around.
-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
-
 -- | If an error can be associated to a particular field in the GraphQL result,
 -- it must contain an entry with the key path that details the path of the
 -- response field which experienced the error. This allows clients to identify
@@ -129,8 +101,13 @@ instance Show ResolverException where
 
 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
@@ -139,3 +116,41 @@ 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

src/Language/GraphQL/Execute.hs

@@ -1,4 +1,13 @@
-{-# LANGUAGE ExplicitForAll #-}
+{- 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 DataKinds #-}
+{-# LANGUAGE ExistentialQuantification #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE ViewPatterns #-}
+{-# LANGUAGE TypeApplications #-}
 
 -- | This module provides functions to execute a @GraphQL@ request.
 module Language.GraphQL.Execute
@@ -6,27 +15,210 @@ module Language.GraphQL.Execute
     , module Language.GraphQL.Execute.Coerce
     ) where
 
-import Control.Monad.Catch (MonadCatch)
-import Data.HashMap.Strict (HashMap)
-import Data.Sequence (Seq(..))
-import Data.Text (Text)
+import Conduit (mapMC, (.|))
+import Control.Arrow (left)
+import Control.Monad.Catch
+     ( Exception(..)
+     , Handler(..)
+     , MonadCatch(..)
+     , MonadThrow(..)
+     , SomeException(..)
+     , catches
+     )
+import Control.Monad.Trans.Class (MonadTrans(..))
+import Control.Monad.Trans.Reader (ReaderT(..), ask, runReaderT)
+import Control.Monad.Trans.Writer (WriterT(..), runWriterT)
+import qualified Control.Monad.Trans.Writer as Writer
+import Control.Monad (foldM)
 import qualified Language.GraphQL.AST.Document as Full
+import Data.Foldable (find)
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HashMap
+import Data.List.NonEmpty (NonEmpty(..))
+import qualified Data.List.NonEmpty as NonEmpty
+import Data.Maybe (fromMaybe)
+import Data.Sequence (Seq)
+import qualified Data.Sequence as Seq
+import Data.Text (Text)
+import qualified Data.Text as Text
+import Data.Typeable (cast)
+import GHC.Records (HasField(..))
 import Language.GraphQL.Execute.Coerce
-import Language.GraphQL.Execute.Execution
-import Language.GraphQL.Execute.Internal
+import Language.GraphQL.Execute.OrderedMap (OrderedMap)
+import qualified Language.GraphQL.Execute.OrderedMap as OrderedMap
 import qualified Language.GraphQL.Execute.Transform as Transform
-import qualified Language.GraphQL.Execute.Subscribe as Subscribe
-import Language.GraphQL.Error
-    ( Error
-    , ResponseEventStream
-    , Response(..)
-    , runCollectErrs
-    )
-import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.Type.In as In
 import qualified Language.GraphQL.Type.Out as Out
-import Language.GraphQL.Type.Schema
+import qualified Language.GraphQL.Type as Type
+import qualified Language.GraphQL.Type.Internal as Type.Internal
+import Language.GraphQL.Type.Schema (Schema, Type)
+import qualified Language.GraphQL.Type.Schema as Schema
+import Language.GraphQL.Error
+    ( Error(..)
+    , Response(..)
+    , Path(..)
+    , ResolverException(..)
+    , ResponseEventStream
+    )
 import Prelude hiding (null)
 
+newtype ExecutorT m a = ExecutorT
+    { runExecutorT :: ReaderT (HashMap Full.Name (Type m)) (WriterT (Seq Error) m) a
+    }
+
+instance Functor m => Functor (ExecutorT m) where
+    fmap f = ExecutorT . fmap f . runExecutorT
+
+instance Applicative m => Applicative (ExecutorT m) where
+    pure = ExecutorT . pure
+    ExecutorT f <*> ExecutorT x = ExecutorT $ f <*> x
+
+instance Monad m => Monad (ExecutorT m) where
+    ExecutorT x >>= f = ExecutorT $ x >>= runExecutorT . f
+
+instance MonadTrans ExecutorT where
+    lift = ExecutorT . lift . lift
+
+instance MonadThrow m => MonadThrow (ExecutorT m) where
+    throwM = lift . throwM
+
+instance MonadCatch m => MonadCatch (ExecutorT m) where
+  catch (ExecutorT stack) handler =
+      ExecutorT $ catch stack $ runExecutorT . handler
+
+data GraphQLException = forall e. Exception e => GraphQLException e
+
+instance Show GraphQLException where
+    show (GraphQLException e) = show e
+
+instance Exception GraphQLException
+
+graphQLExceptionToException :: Exception e => e -> SomeException
+graphQLExceptionToException = toException . GraphQLException
+
+graphQLExceptionFromException :: Exception e => SomeException -> Maybe e
+graphQLExceptionFromException e = do
+    GraphQLException graphqlException <- fromException e
+    cast graphqlException
+
+data ResultException = forall e. Exception e => ResultException e
+
+instance Show ResultException where
+    show (ResultException e) = show e
+
+instance Exception ResultException where
+    toException = graphQLExceptionToException
+    fromException = graphQLExceptionFromException
+
+resultExceptionToException :: Exception e => e -> SomeException
+resultExceptionToException = toException . ResultException
+
+resultExceptionFromException :: Exception e => SomeException -> Maybe e
+resultExceptionFromException e = do
+    ResultException resultException <- fromException e
+    cast resultException
+
+data FieldException = forall e. Exception e => FieldException Full.Location [Path] e
+
+instance Show FieldException where
+    show (FieldException _ _ e) = displayException e
+
+instance Exception FieldException where
+    toException = graphQLExceptionToException
+    fromException = graphQLExceptionFromException
+
+data ValueCompletionException = ValueCompletionException String Type.Value
+
+instance Show ValueCompletionException where
+    show (ValueCompletionException typeRepresentation found) = concat
+        [ "Value completion error. Expected type "
+        , typeRepresentation
+        , ", found: "
+        , show found
+        , "."
+        ]
+
+instance Exception ValueCompletionException where
+    toException = resultExceptionToException
+    fromException = resultExceptionFromException
+
+data InputCoercionException =
+    InputCoercionException String In.Type (Maybe (Full.Node Transform.Input))
+
+instance Show InputCoercionException where
+    show (InputCoercionException argumentName argumentType Nothing) = concat
+        [ "Required argument \""
+        , argumentName
+        , "\" of type "
+        , show argumentType
+        , " not specified."
+        ]
+    show (InputCoercionException argumentName argumentType (Just givenValue)) = concat
+        [ "Argument \""
+        , argumentName
+        , "\" has invalid type. Expected type "
+        , show argumentType
+        , ", found: "
+        , show givenValue
+        , "."
+        ]
+
+instance Exception InputCoercionException where
+    toException = graphQLExceptionToException
+    fromException = graphQLExceptionFromException
+
+newtype ResultCoercionException = ResultCoercionException String
+
+instance Show ResultCoercionException where
+    show (ResultCoercionException typeRepresentation) = concat
+        [ "Unable to coerce result to "
+        , typeRepresentation
+        , "."
+        ]
+
+instance Exception ResultCoercionException where
+    toException = resultExceptionToException
+    fromException = resultExceptionFromException
+
+-- | Query error types.
+data QueryError
+    = OperationNameRequired
+    | OperationNotFound String
+    | CoercionError Full.VariableDefinition
+    | UnknownInputType Full.VariableDefinition
+
+tell :: Monad m => Seq Error -> ExecutorT m ()
+tell = ExecutorT . lift . Writer.tell
+
+queryError :: QueryError -> Error
+queryError OperationNameRequired =
+    Error{ message = "Operation name is required.", locations = [], path = [] }
+queryError (OperationNotFound operationName) =
+    let queryErrorMessage = Text.concat
+            [ "Operation \""
+            , Text.pack operationName
+            , "\" not found."
+            ]
+     in Error{ message = queryErrorMessage, locations = [], path = [] }
+queryError (CoercionError variableDefinition) =
+    let Full.VariableDefinition variableName _ _ location = variableDefinition
+        queryErrorMessage = Text.concat
+            [ "Failed to coerce the variable \""
+            , variableName
+            , "\"."
+            ]
+     in Error{ message = queryErrorMessage, locations = [location], path = [] }
+queryError (UnknownInputType variableDefinition) =
+    let Full.VariableDefinition variableName variableTypeName _ location = variableDefinition
+        queryErrorMessage = Text.concat
+            [ "Variable \""
+            , variableName
+            , "\" has unknown type \""
+            , Text.pack $ show variableTypeName
+            , "\"."
+            ]
+     in Error{ message = queryErrorMessage, locations = [location], path = [] }
+
 -- | The substitution is applied to the document, and the resolvers are applied
 -- to the resulting fields. The operation name can be used if the document
 -- defines multiple root operations.
@@ -39,33 +231,492 @@ execute :: (MonadCatch m, VariableValue a, Serialize b)
     -> HashMap Full.Name a -- ^ Variable substitution function.
     -> Full.Document -- @GraphQL@ document.
     -> m (Either (ResponseEventStream m b) (Response b))
-execute schema' operationName subs document
-    = either (pure . rightErrorResponse . singleError [] . show) executeRequest
-    $ Transform.document schema' operationName subs document
+execute schema' operationName subs document' =
+    executeRequest schema' document' (Text.unpack <$> operationName) subs
 
-executeRequest :: (MonadCatch m, Serialize a)
-    => Transform.Document m
+executeRequest :: (MonadCatch m, Serialize a, VariableValue b)
+    => Schema m
+    -> Full.Document
+    -> Maybe String
+    -> HashMap Full.Name b
     -> m (Either (ResponseEventStream m a) (Response a))
-executeRequest (Transform.Document types' rootObjectType operation)
-    | (Transform.Query _ fields objectLocation) <- operation =
-        Right <$> executeOperation types' rootObjectType objectLocation fields
-    | (Transform.Mutation _ fields objectLocation) <- operation =
-        Right <$> executeOperation types' rootObjectType objectLocation fields
-    | (Transform.Subscription _ fields objectLocation) <- operation
-        = either rightErrorResponse Left
-        <$> Subscribe.subscribe types' rootObjectType objectLocation fields
+executeRequest schema sourceDocument operationName variableValues = do
+    operationAndVariables <- sequence buildOperation
+    case operationAndVariables of
+        Left queryError' -> pure
+            $ Right
+            $ Response null $ pure $ queryError queryError'
+        Right operation
+            | Transform.Operation Full.Query topSelections _operationLocation <- operation ->
+                 Right <$> executeQuery topSelections schema
+            | Transform.Operation Full.Mutation topSelections operationLocation <- operation ->
+                Right <$> executeMutation topSelections schema operationLocation
+            | Transform.Operation Full.Subscription topSelections operationLocation <- operation ->
+                either rightErrorResponse Left <$> subscribe topSelections schema operationLocation
+  where
+    schemaTypes = Schema.types schema
+    (operationDefinitions, fragmentDefinitions') =
+        Transform.document sourceDocument
+    buildOperation = do
+        operationDefinition <- getOperation operationDefinitions operationName
+        coercedVariableValues <- coerceVariableValues
+            schemaTypes
+            operationDefinition
+            variableValues
+        let replacement = Transform.Replacement
+                { variableValues = coercedVariableValues
+                , fragmentDefinitions = fragmentDefinitions'
+                , visitedFragments = mempty
+                , types = schemaTypes
+                }
+        pure $ flip runReaderT replacement
+            $ Transform.runTransformT
+            $ Transform.transform operationDefinition
 
--- This is actually executeMutation, but we don't distinguish between queries
--- and mutations yet.
-executeOperation :: (MonadCatch m, Serialize a)
+rightErrorResponse :: Serialize b => forall a. Error -> Either a (Response b)
+rightErrorResponse = Right . Response null . pure
+
+getOperation :: [Full.OperationDefinition] -> Maybe String -> Either QueryError Full.OperationDefinition
+getOperation [operation] Nothing = Right operation
+getOperation operations (Just givenOperationName)
+    = maybe (Left $ OperationNotFound givenOperationName) Right
+    $ find findOperationByName operations
+  where
+    findOperationByName (Full.OperationDefinition _ (Just operationName) _ _ _ _) =
+        givenOperationName == Text.unpack operationName
+    findOperationByName _ = False
+getOperation _ _ = Left OperationNameRequired
+
+executeQuery :: (MonadCatch m, Serialize a)
+    => Seq (Transform.Selection m)
+    -> Schema m
+    -> m (Response a)
+executeQuery topSelections schema = do
+    let queryType = Schema.query schema
+    (data', errors) <- runWriterT
+        $ flip runReaderT (Schema.types schema)
+        $ runExecutorT
+        $ catch (executeSelectionSet topSelections queryType Type.Null [])
+        handleException
+    pure $ Response data' errors
+
+handleException :: (MonadCatch m, Serialize a)
+    => FieldException
+    -> ExecutorT m a
+handleException (FieldException fieldLocation errorPath next) =
+    let newError = constructError next fieldLocation errorPath
+     in tell (Seq.singleton newError) >> pure null
+
+constructError :: Exception e => e -> Full.Location -> [Path] -> Error
+constructError e fieldLocation errorPath = Error
+    { message = Text.pack (displayException e)
+    , path = reverse errorPath
+    , locations = [fieldLocation]
+    }
+
+executeMutation :: (MonadCatch m, Serialize a)
+    => Seq (Transform.Selection m)
+    -> Schema m
+    -> Full.Location
+    -> m (Response a)
+executeMutation topSelections schema operationLocation
+    | Just mutationType <- Schema.mutation schema = do
+        (data', errors) <- runWriterT
+            $ flip runReaderT (Schema.types schema)
+            $ runExecutorT
+            $ catch (executeSelectionSet topSelections mutationType Type.Null [])
+            handleException
+        pure $ Response data' errors
+    | otherwise = pure
+        $ Response null
+        $ Seq.singleton
+        $ Error "Schema doesn't support mutations." [operationLocation] []
+
+executeSelectionSet :: (MonadCatch m, Serialize a)
+    => Seq (Transform.Selection m)
+    -> Out.ObjectType m
+    -> Type.Value
+    -> [Path]
+    -> ExecutorT m a
+executeSelectionSet selections objectType objectValue errorPath = do
+    let groupedFieldSet = collectFields objectType selections
+    resolvedValues <- OrderedMap.traverseMaybe go groupedFieldSet
+    coerceResult (Out.NonNullObjectType objectType) $ Object resolvedValues
+  where
+    executeField' fields resolver =
+        executeField objectValue fields resolver errorPath
+    Out.ObjectType _ _ _ resolvers = objectType
+    go fields@(Transform.Field _ fieldName _ _ _ :| _) =
+        traverse (executeField' fields) $ HashMap.lookup fieldName resolvers
+
+fieldsSegment :: forall m. NonEmpty (Transform.Field m) -> Path
+fieldsSegment (Transform.Field alias fieldName _ _ _ :| _) =
+    Segment (fromMaybe fieldName alias)
+
+viewResolver :: Out.Resolver m -> (Out.Field m, Out.Resolve m)
+viewResolver (Out.ValueResolver resolverField' resolveFunction) =
+    (resolverField', resolveFunction)
+viewResolver (Out.EventStreamResolver resolverField' resolveFunction _) =
+    (resolverField', resolveFunction)
+
+executeField :: forall m a
+    . (MonadCatch m, Serialize a)
+    => Type.Value
+    -> NonEmpty (Transform.Field m)
+    -> Out.Resolver m
+    -> [Path]
+    -> ExecutorT m a
+executeField objectValue fields (viewResolver -> resolverPair) errorPath =
+    let Transform.Field _ fieldName inputArguments _ fieldLocation :| _ = fields
+     in catches (go fieldName inputArguments)
+        [ Handler nullResultHandler
+        , Handler (inputCoercionHandler fieldLocation)
+        , Handler (resultHandler fieldLocation)
+        , Handler (resolverHandler fieldLocation)
+        ]
+  where
+    inputCoercionHandler :: (MonadCatch m, Serialize a)
+        => Full.Location
+        -> InputCoercionException
+        -> ExecutorT m a
+    inputCoercionHandler _ e@(InputCoercionException _ _ (Just valueNode)) =
+        let argumentLocation = getField @"location" valueNode
+         in exceptionHandler argumentLocation e
+    inputCoercionHandler fieldLocation e = exceptionHandler fieldLocation e
+    resultHandler :: (MonadCatch m, Serialize a)
+        => Full.Location
+        -> ResultException
+        -> ExecutorT m a
+    resultHandler = exceptionHandler
+    resolverHandler :: (MonadCatch m, Serialize a)
+        => Full.Location
+        -> ResolverException
+        -> ExecutorT m a
+    resolverHandler = exceptionHandler
+    nullResultHandler :: (MonadCatch m, Serialize a)
+        => FieldException
+        -> ExecutorT m a
+    nullResultHandler e@(FieldException fieldLocation errorPath' next) =
+        let newError = constructError next fieldLocation errorPath'
+         in if Out.isNonNullType fieldType
+             then throwM e
+             else returnError newError
+    exceptionHandler errorLocation e =
+        let newPath = fieldsSegment fields : errorPath
+            newError = constructError e errorLocation newPath
+         in if Out.isNonNullType fieldType
+             then throwM $ FieldException errorLocation newPath 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
+    (resolverField, resolveFunction) = resolverPair
+    Out.Field _ fieldType argumentTypes = resolverField
+
+resolveFieldValue :: MonadCatch m
+    => Out.Resolve m
+    -> Type.Value
+    -> Full.Name
+    -> Type.Subs
+    -> ExecutorT m Type.Value
+resolveFieldValue resolver objectValue _fieldName argumentValues =
+    lift $ runReaderT resolver context
+  where
+    context = Type.Context
+        { Type.arguments = Type.Arguments argumentValues
+        , Type.values = objectValue
+        }
+
+resolveAbstractType :: Monad m
+    => Type.Internal.AbstractType m
+    -> Type.Subs
+    -> ExecutorT m (Maybe (Out.ObjectType m))
+resolveAbstractType abstractType values'
+    | Just (Type.String typeName) <- HashMap.lookup "__typename" values' = do
+        types' <- ExecutorT ask
+        case HashMap.lookup typeName types' of
+            Just (Type.Internal.ObjectType objectType) ->
+                if Type.Internal.instanceOf objectType abstractType
+                    then pure $ Just objectType
+                    else pure Nothing
+            _ -> pure Nothing
+    | otherwise = pure Nothing
+
+completeValue :: (MonadCatch m, Serialize a)
+    => Out.Type m
+    -> NonEmpty (Transform.Field m)
+    -> [Path]
+    -> Type.Value
+    -> ExecutorT m 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
+  where
+    go (index, accumulator) listItem = do
+        let updatedPath = Index index : errorPath
+        completedValue <- completeValue listType fields updatedPath listItem
+        pure (index + 1, completedValue : accumulator)
+completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Int int) =
+    coerceResult outputType $ Int int
+completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Boolean boolean) =
+    coerceResult outputType $ Boolean boolean
+completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.Float float) =
+    coerceResult outputType $ Float float
+completeValue outputType@(Out.ScalarBaseType _) _ _ (Type.String string) =
+    coerceResult outputType $ String string
+completeValue outputType@(Out.EnumBaseType enumType) _ _ (Type.Enum enum) =
+    let Type.EnumType _ _ enumMembers = enumType
+     in if HashMap.member enum enumMembers
+        then coerceResult outputType $ Enum enum
+        else throwM
+            $ ValueCompletionException (show outputType)
+            $ Type.Enum enum
+completeValue (Out.ObjectBaseType objectType) fields errorPath result
+    = executeSelectionSet (mergeSelectionSets fields) objectType result
+    $ fieldsSegment fields : errorPath
+completeValue outputType@(Out.InterfaceBaseType interfaceType) fields errorPath result
+    | Type.Object objectMap <- result = do
+        let abstractType = Type.Internal.AbstractInterfaceType interfaceType
+        concreteType <- resolveAbstractType abstractType objectMap
+        case concreteType of
+            Just objectType
+                -> executeSelectionSet (mergeSelectionSets fields) objectType result
+                $ fieldsSegment fields : errorPath
+            Nothing -> throwM
+                $ ValueCompletionException (show outputType) result
+completeValue outputType@(Out.UnionBaseType unionType) fields errorPath result
+    | Type.Object objectMap <- result = do
+        let abstractType = Type.Internal.AbstractUnionType unionType
+        concreteType <- resolveAbstractType abstractType objectMap
+        case concreteType of
+            Just objectType
+                -> executeSelectionSet (mergeSelectionSets fields) objectType result
+                $ fieldsSegment fields : errorPath
+            Nothing -> throwM
+                $ ValueCompletionException (show outputType) result
+completeValue outputType _ _ result =
+    throwM $ ValueCompletionException (show outputType) result
+
+coerceResult :: (MonadCatch m, Serialize a)
+    => Out.Type m
+    -> Output a
+    -> ExecutorT m a
+coerceResult outputType result
+    | Just serialized <- serialize outputType result = pure serialized
+    | otherwise = throwM $ ResultCoercionException $ show outputType
+
+mergeSelectionSets :: MonadCatch m
+    => NonEmpty (Transform.Field m)
+    -> Seq (Transform.Selection m)
+mergeSelectionSets = foldr forEach mempty
+  where
+    forEach (Transform.Field _ _ _ fieldSelectionSet _) selectionSet' =
+        selectionSet' <> fieldSelectionSet
+
+coerceArgumentValues :: MonadCatch m
+    => HashMap Full.Name In.Argument
+    -> HashMap Full.Name (Full.Node Transform.Input)
+    -> m Type.Subs
+coerceArgumentValues argumentDefinitions argumentValues =
+    HashMap.foldrWithKey c pure argumentDefinitions mempty
+  where
+    c argumentName argumentType pure' resultMap =
+        forEach argumentName argumentType resultMap >>= pure'
+    forEach :: MonadCatch m
+         => Full.Name
+         -> In.Argument
+         -> Type.Subs
+         -> m Type.Subs
+    forEach argumentName (In.Argument _ variableType defaultValue) resultMap = do
+        let matchedMap
+                = matchFieldValues' argumentName variableType defaultValue
+                $ Just resultMap
+         in case matchedMap of
+            Just matchedValues -> pure matchedValues
+            Nothing
+                | Just inputValue <- HashMap.lookup argumentName argumentValues
+                    -> throwM
+                    $ InputCoercionException (Text.unpack argumentName) variableType
+                    $ 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 <$> resultMap
+    coerceArgumentValue _ (Transform.Variable variable) = pure variable
+    coerceArgumentValue _ _ = Nothing
+    forEachField object variableName (In.InputField _ variableType defaultValue) =
+        matchFieldValues coerceArgumentValue object variableName variableType defaultValue
+
+collectFields :: Monad m
+    => Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> OrderedMap (NonEmpty (Transform.Field m))
+collectFields objectType = foldl forEach OrderedMap.empty
+  where
+    forEach groupedFields (Transform.FieldSelection fieldSelection) =
+        let Transform.Field maybeAlias fieldName _ _ _ = fieldSelection
+            responseKey = fromMaybe fieldName maybeAlias
+         in OrderedMap.insert responseKey (fieldSelection :| []) groupedFields
+    forEach groupedFields (Transform.FragmentSelection selectionFragment)
+        | Transform.Fragment fragmentType fragmentSelectionSet _ <- selectionFragment
+        , Type.Internal.doesFragmentTypeApply fragmentType objectType =
+            let fragmentGroupedFieldSet =
+                    collectFields objectType fragmentSelectionSet
+             in groupedFields <> fragmentGroupedFieldSet
+        | otherwise = groupedFields
+
+coerceVariableValues :: (Monad m, VariableValue b)
+    => HashMap Full.Name (Schema.Type m)
+    -> Full.OperationDefinition
+    -> HashMap Full.Name b
+    -> Either QueryError Type.Subs
+coerceVariableValues types operationDefinition' variableValues
+    | Full.OperationDefinition _ _ variableDefinitions _ _ _ <-
+        operationDefinition'
+    = foldr forEach (Right HashMap.empty) variableDefinitions
+    | otherwise = pure mempty
+  where
+    forEach variableDefinition (Right coercedValues) =
+        let Full.VariableDefinition variableName variableTypeName defaultValue _ =
+                variableDefinition
+            defaultValue' = constValue . Full.node <$> defaultValue
+         in case Type.Internal.lookupInputType variableTypeName types of
+            Just variableType ->
+                maybe (Left $ CoercionError variableDefinition) Right
+                    $ matchFieldValues
+                        coerceVariableValue'
+                        variableValues
+                        variableName
+                        variableType
+                        defaultValue'
+                    $ Just coercedValues
+            Nothing -> Left $ UnknownInputType variableDefinition
+    forEach _ coercedValuesOrError = coercedValuesOrError
+    coerceVariableValue' variableType value'
+        = coerceVariableValue variableType value'
+        >>= coerceInputLiteral variableType
+
+constValue :: Full.ConstValue -> Type.Value
+constValue (Full.ConstInt i) = Type.Int i
+constValue (Full.ConstFloat f) = Type.Float f
+constValue (Full.ConstString x) = Type.String x
+constValue (Full.ConstBoolean b) = Type.Boolean b
+constValue Full.ConstNull = Type.Null
+constValue (Full.ConstEnum e) = Type.Enum e
+constValue (Full.ConstList list) = Type.List $ constValue . Full.node <$> list
+constValue (Full.ConstObject o) =
+    Type.Object $ HashMap.fromList $ constObjectField <$> o
+  where
+    constObjectField Full.ObjectField{value = value', ..} =
+        (name, constValue $ Full.node value')
+
+subscribe :: (MonadCatch m, Serialize a)
+    => Seq (Transform.Selection m)
+    -> Schema m
+    -> Full.Location
+    -> m (Either Error (ResponseEventStream m a))
+subscribe fields schema objectLocation
+    | Just objectType <- Schema.subscription schema = do
+        let types' = Schema.types schema
+        sourceStream <-
+            createSourceEventStream types' objectType objectLocation fields
+        let traverser =
+                mapSourceToResponseEvent types' objectType fields
+        traverse traverser sourceStream
+    | otherwise = pure $ Left
+        $ Error "Schema doesn't support subscriptions." [] []
+
+mapSourceToResponseEvent :: (MonadCatch m, Serialize a)
+    => HashMap Full.Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> Out.SourceEventStream m
+    -> m (ResponseEventStream m a)
+mapSourceToResponseEvent types' subscriptionType fields sourceStream
+    = pure
+    $ sourceStream
+    .| mapMC (executeSubscriptionEvent types' subscriptionType fields)
+
+createSourceEventStream :: MonadCatch m
     => HashMap Full.Name (Type m)
     -> Out.ObjectType m
     -> Full.Location
     -> Seq (Transform.Selection m)
-    -> m (Response a)
-executeOperation types' objectType objectLocation fields
-    = runCollectErrs types'
-    $ executeSelectionSet Definition.Null objectType objectLocation fields
+    -> m (Either Error (Out.SourceEventStream m))
+createSourceEventStream _types subscriptionType objectLocation fields
+    | [fieldGroup] <- OrderedMap.elems groupedFieldSet
+    , Transform.Field _ fieldName arguments' _ errorLocation <-
+        NonEmpty.head fieldGroup
+    , Out.ObjectType _ _ _ fieldTypes <- subscriptionType
+    , resolverT <- fieldTypes HashMap.! fieldName
+    , Out.EventStreamResolver fieldDefinition _ resolver <- resolverT
+    , Out.Field _ _fieldType argumentDefinitions <- fieldDefinition =
+        case coerceArgumentValues argumentDefinitions arguments' of
+            Left _ -> pure
+                $ Left
+                $ Error "Argument coercion failed." [errorLocation] []
+            Right  argumentValues -> left (singleError [errorLocation])
+                <$> resolveFieldEventStream Type.Null argumentValues resolver
+    | otherwise = pure
+        $ Left
+        $ Error "Subscription contains more than one field." [objectLocation] []
+  where
+    groupedFieldSet = collectFields subscriptionType fields
+    singleError :: [Full.Location] -> String -> Error
+    singleError errorLocations message = Error (Text.pack message) errorLocations []
 
-rightErrorResponse :: Serialize b => forall a. Error -> Either a (Response b)
-rightErrorResponse = Right . Response null . pure
+resolveFieldEventStream :: MonadCatch m
+    => Type.Value
+    -> Type.Subs
+    -> Out.Subscribe m
+    -> m (Either String (Out.SourceEventStream m))
+resolveFieldEventStream result args resolver =
+    catch (Right <$> runReaderT resolver context) handleEventStreamError
+  where
+    handleEventStreamError :: MonadCatch m
+        => ResolverException
+        -> m (Either String (Out.SourceEventStream m))
+    handleEventStreamError = pure . Left . displayException
+    context = Type.Context
+        { Type.arguments = Type.Arguments args
+        , Type.values = result
+        }
+
+executeSubscriptionEvent :: (MonadCatch m, Serialize a)
+    => HashMap Full.Name (Type m)
+    -> Out.ObjectType m
+    -> Seq (Transform.Selection m)
+    -> Type.Value
+    -> m (Response a)
+executeSubscriptionEvent types' objectType fields initialValue = do
+    (data', errors) <- runWriterT
+        $ flip runReaderT types'
+        $ runExecutorT
+        $ catch (executeSelectionSet fields objectType initialValue [])
+        handleException
+    pure $ Response data' errors

src/Language/GraphQL/Execute/Execution.hs

@@ -1,253 +0,0 @@
-{-# LANGUAGE ExplicitForAll #-}
-{-# LANGUAGE LambdaCase #-}
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE ViewPatterns #-}
-
-module Language.GraphQL.Execute.Execution
-    ( coerceArgumentValues
-    , collectFields
-    , executeSelectionSet
-    ) where
-
-import Control.Monad.Catch (Exception(..), MonadCatch(..))
-import Control.Monad.Trans.Class (lift)
-import Control.Monad.Trans.Reader (runReaderT)
-import Control.Monad.Trans.State (gets)
-import Data.List.NonEmpty (NonEmpty(..))
-import qualified Data.List.NonEmpty as NonEmpty
-import Data.HashMap.Strict (HashMap)
-import qualified Data.HashMap.Strict as HashMap
-import Data.Maybe (fromMaybe)
-import Data.Sequence (Seq(..))
-import qualified Data.Text as Text
-import qualified Language.GraphQL.AST as Full
-import Language.GraphQL.Error
-import Language.GraphQL.Execute.Coerce
-import Language.GraphQL.Execute.Internal
-import Language.GraphQL.Execute.OrderedMap (OrderedMap)
-import qualified Language.GraphQL.Execute.OrderedMap as OrderedMap
-import qualified Language.GraphQL.Execute.Transform as Transform
-import qualified Language.GraphQL.Type as Type
-import qualified Language.GraphQL.Type.In as In
-import qualified Language.GraphQL.Type.Out as Out
-import qualified Language.GraphQL.Type.Internal as Internal
-import Prelude hiding (null)
-
-resolveFieldValue :: MonadCatch m
-    => Type.Value
-    -> Type.Subs
-    -> Type.Resolve m
-    -> Full.Location
-    -> CollectErrsT m Type.Value
-resolveFieldValue result args resolver location' =
-    catch (lift $ runReaderT resolver context) handleFieldError
-  where
-    handleFieldError :: MonadCatch m
-        => ResolverException
-        -> CollectErrsT m Type.Value
-    handleFieldError e
-        = addError Type.Null
-        $ Error (Text.pack $ displayException e) [location'] []
-    context = Type.Context
-        { Type.arguments = Type.Arguments args
-        , Type.values = result
-        }
-
-collectFields :: Monad m
-    => Out.ObjectType m
-    -> Seq (Transform.Selection m)
-    -> OrderedMap (NonEmpty (Transform.Field m))
-collectFields objectType = foldl forEach OrderedMap.empty
-  where
-    forEach groupedFields (Transform.SelectionField field) =
-        let responseKey = aliasOrName field
-         in OrderedMap.insert responseKey (field :| []) groupedFields
-    forEach groupedFields (Transform.SelectionFragment selectionFragment)
-        | Transform.Fragment fragmentType fragmentSelectionSet <- selectionFragment
-        , Internal.doesFragmentTypeApply fragmentType objectType =
-            let fragmentGroupedFieldSet = collectFields objectType fragmentSelectionSet
-             in groupedFields <> fragmentGroupedFieldSet
-        | otherwise = groupedFields
-
-aliasOrName :: forall m. Transform.Field m -> Full.Name
-aliasOrName (Transform.Field alias name _ _ _) = fromMaybe name alias
-
-resolveAbstractType :: Monad m
-    => Internal.AbstractType m
-    -> Type.Subs
-    -> CollectErrsT m (Maybe (Out.ObjectType m))
-resolveAbstractType abstractType values'
-    | Just (Type.String typeName) <- HashMap.lookup "__typename" values' = do
-        types' <- gets types
-        case HashMap.lookup typeName types' of
-            Just (Internal.ObjectType objectType) ->
-                if Internal.instanceOf objectType abstractType
-                    then pure $ Just objectType
-                    else pure Nothing
-            _ -> pure Nothing
-    | otherwise = pure Nothing
-
-executeField :: (MonadCatch m, Serialize a)
-    => Out.Resolver m
-    -> Type.Value
-    -> NonEmpty (Transform.Field m)
-    -> CollectErrsT m a
-executeField fieldResolver prev fields
-    | Out.ValueResolver fieldDefinition resolver <- fieldResolver =
-        executeField' fieldDefinition resolver
-    | Out.EventStreamResolver fieldDefinition resolver _ <- fieldResolver =
-        executeField' fieldDefinition resolver
-  where
-    executeField' fieldDefinition resolver = do
-        let Out.Field _ fieldType argumentDefinitions = fieldDefinition
-        let Transform.Field _ _ arguments' _ location' = NonEmpty.head fields
-        case coerceArgumentValues argumentDefinitions arguments' of
-            Left [] ->
-                let errorMessage = "Not all required arguments are specified."
-                 in addError null $ Error errorMessage [location'] []
-            Left errorLocations -> addError null
-                $ Error "Argument coercing failed." errorLocations []
-            Right argumentValues -> do
-                answer <- resolveFieldValue prev argumentValues resolver location'
-                completeValue fieldType fields answer
-
-completeValue :: (MonadCatch m, Serialize a)
-    => Out.Type m
-    -> NonEmpty (Transform.Field m)
-    -> Type.Value
-    -> CollectErrsT m a
-completeValue (Out.isNonNullType -> False) _ Type.Null = pure null
-completeValue outputType@(Out.ListBaseType listType) fields (Type.List list)
-    = traverse (completeValue listType fields) list
-    >>= coerceResult outputType (firstFieldLocation fields) . List
-completeValue outputType@(Out.ScalarBaseType _) fields (Type.Int int) =
-    coerceResult outputType (firstFieldLocation fields) $ Int int
-completeValue outputType@(Out.ScalarBaseType _) fields (Type.Boolean boolean) =
-    coerceResult outputType (firstFieldLocation fields) $ Boolean boolean
-completeValue outputType@(Out.ScalarBaseType _) fields (Type.Float float) =
-    coerceResult outputType (firstFieldLocation fields) $ Float float
-completeValue outputType@(Out.ScalarBaseType _) fields (Type.String string) =
-    coerceResult outputType (firstFieldLocation fields) $ String string
-completeValue outputType@(Out.EnumBaseType enumType) fields (Type.Enum enum) =
-    let Type.EnumType _ _ enumMembers = enumType
-        location = firstFieldLocation fields
-     in if HashMap.member enum enumMembers
-        then coerceResult outputType location $ Enum enum
-        else addError null $ Error "Enum value completion failed." [location] []
-completeValue (Out.ObjectBaseType objectType) fields result
-    = executeSelectionSet result objectType (firstFieldLocation fields)
-    $ mergeSelectionSets fields
-completeValue (Out.InterfaceBaseType interfaceType) fields result
-    | Type.Object objectMap <- result = do
-        let abstractType = Internal.AbstractInterfaceType interfaceType
-        let location = firstFieldLocation fields
-        concreteType <- resolveAbstractType abstractType objectMap
-        case concreteType of
-            Just objectType -> executeSelectionSet result objectType location
-                $ mergeSelectionSets fields
-            Nothing -> addError null
-                $ Error "Interface value completion failed." [location] []
-completeValue (Out.UnionBaseType unionType) fields result
-    | Type.Object objectMap <- result = do
-        let abstractType = Internal.AbstractUnionType unionType
-        let  location = firstFieldLocation fields
-        concreteType <- resolveAbstractType abstractType objectMap
-        case concreteType of
-            Just objectType -> executeSelectionSet result objectType
-                location $ mergeSelectionSets fields
-            Nothing -> addError null
-                $ Error "Union value completion failed." [location] []
-completeValue _ (Transform.Field _ _ _ _ location :| _) _ =
-    addError null $ Error "Value completion failed." [location] []
-
-mergeSelectionSets :: MonadCatch m
-    => NonEmpty (Transform.Field m)
-    -> Seq (Transform.Selection m)
-mergeSelectionSets = foldr forEach mempty
-  where
-    forEach (Transform.Field _ _ _ fieldSelectionSet _) selectionSet =
-        selectionSet <> fieldSelectionSet
-
-firstFieldLocation :: MonadCatch m => NonEmpty (Transform.Field m) -> Full.Location
-firstFieldLocation (Transform.Field _ _ _ _ fieldLocation :| _) = fieldLocation
-
-coerceResult :: (MonadCatch m, Serialize a)
-    => Out.Type m
-    -> Full.Location
-    -> Output a
-    -> CollectErrsT m a
-coerceResult outputType parentLocation result
-    | Just serialized <- serialize outputType result = pure serialized
-    | otherwise = addError null
-        $ Error "Result coercion failed." [parentLocation] []
-
--- | Takes an 'Out.ObjectType' and a list of 'Transform.Selection's and applies
--- each field to each 'Transform.Selection'. Resolves into a value containing
--- the resolved 'Transform.Selection', or a null value and error information.
-executeSelectionSet :: (MonadCatch m, Serialize a)
-    => Type.Value
-    -> Out.ObjectType m
-    -> Full.Location
-    -> Seq (Transform.Selection m)
-    -> CollectErrsT m a
-executeSelectionSet result objectType@(Out.ObjectType _ _ _ resolvers) objectLocation selectionSet = do
-    let fields = collectFields objectType selectionSet
-    resolvedValues <- OrderedMap.traverseMaybe forEach fields
-    coerceResult (Out.NonNullObjectType objectType) objectLocation
-        $ Object resolvedValues
-  where
-    forEach fields@(field :| _) =
-        let Transform.Field _ name _ _ _ = field
-         in traverse (tryResolver fields) $ lookupResolver name
-    lookupResolver = flip HashMap.lookup resolvers
-    tryResolver fields resolver =
-        executeField resolver result fields >>= lift . pure
-
-coerceArgumentValues
-    :: HashMap Full.Name In.Argument
-    -> HashMap Full.Name (Full.Node Transform.Input)
-    -> Either [Full.Location] Type.Subs
-coerceArgumentValues argumentDefinitions argumentNodes =
-    HashMap.foldrWithKey forEach (pure mempty) argumentDefinitions
-  where
-    forEach argumentName (In.Argument _ variableType defaultValue) = \case
-        Right resultMap
-            | Just matchedValues
-                <- matchFieldValues' argumentName variableType defaultValue $ Just resultMap
-                -> Right matchedValues
-            | otherwise -> Left $ generateError argumentName []
-        Left errorLocations
-            | Just _
-                <- matchFieldValues' argumentName variableType defaultValue $ pure mempty
-                -> Left errorLocations
-            | otherwise -> Left $ generateError argumentName errorLocations
-    generateError argumentName errorLocations =
-        case HashMap.lookup argumentName argumentNodes of
-            Just (Full.Node _ errorLocation) -> [errorLocation]
-            Nothing -> errorLocations
-    matchFieldValues' = matchFieldValues coerceArgumentValue (Full.node <$> argumentNodes)
-    coerceArgumentValue inputType (Transform.Int integer) =
-        coerceInputLiteral inputType (Type.Int integer)
-    coerceArgumentValue inputType (Transform.Boolean boolean) =
-        coerceInputLiteral inputType (Type.Boolean boolean)
-    coerceArgumentValue inputType (Transform.String string) =
-        coerceInputLiteral inputType (Type.String string)
-    coerceArgumentValue inputType (Transform.Float float) =
-        coerceInputLiteral inputType (Type.Float float)
-    coerceArgumentValue inputType (Transform.Enum enum) =
-        coerceInputLiteral inputType (Type.Enum enum)
-    coerceArgumentValue inputType Transform.Null
-        | In.isNonNullType inputType = Nothing
-        | otherwise = coerceInputLiteral inputType Type.Null
-    coerceArgumentValue (In.ListBaseType inputType) (Transform.List list) =
-        let coerceItem = coerceInputLiteral inputType
-         in Type.List <$> traverse coerceItem list
-    coerceArgumentValue (In.InputObjectBaseType inputType) (Transform.Object object)
-        | In.InputObjectType _ _ inputFields <- inputType = 
-            let go = forEachField object
-                resultMap = HashMap.foldrWithKey go (pure mempty) inputFields
-             in Type.Object <$> resultMap
-    coerceArgumentValue _ (Transform.Variable variable) = pure variable
-    coerceArgumentValue _ _ = Nothing
-    forEachField object variableName (In.InputField _ variableType defaultValue) =
-        matchFieldValues coerceArgumentValue object variableName variableType defaultValue

src/Language/GraphQL/Execute/Internal.hs

@@ -1,31 +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 DuplicateRecordFields #-}
-{-# LANGUAGE ExplicitForAll #-}
-{-# LANGUAGE NamedFieldPuns #-}
-
-module Language.GraphQL.Execute.Internal
-    ( addError
-    , singleError
-    ) where
-
-import Control.Monad.Trans.State (modify)
-import Control.Monad.Catch (MonadCatch)
-import Data.Sequence ((|>))
-import qualified Data.Text as Text
-import qualified Language.GraphQL.AST as Full
-import Language.GraphQL.Error (CollectErrsT, Error(..), Resolution(..))
-import Prelude hiding (null)
-
-addError :: MonadCatch m => forall a. a -> Error -> CollectErrsT m a
-addError returnValue error' = modify appender >> pure returnValue
-  where
-   appender :: Resolution m -> Resolution m
-   appender resolution@Resolution{ errors } = resolution
-       { errors = errors |> error'
-       }
-
-singleError :: [Full.Location] -> String -> Error
-singleError errorLocations message = Error (Text.pack message) errorLocations []

src/Language/GraphQL/Execute/Subscribe.hs

@@ -1,113 +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 ExplicitForAll #-}
-{-# LANGUAGE OverloadedStrings #-}
-module Language.GraphQL.Execute.Subscribe
-    ( subscribe
-    ) where
-
-import Conduit
-import Control.Arrow (left)
-import Control.Monad.Catch (Exception(..), MonadCatch(..))
-import Control.Monad.Trans.Reader (ReaderT(..), runReaderT)
-import Data.HashMap.Strict (HashMap)
-import qualified Data.HashMap.Strict as HashMap
-import qualified Data.List.NonEmpty as NonEmpty
-import Data.Sequence (Seq(..))
-import qualified Language.GraphQL.AST as Full
-import Language.GraphQL.Execute.Coerce
-import Language.GraphQL.Execute.Execution
-import Language.GraphQL.Execute.Internal
-import qualified Language.GraphQL.Execute.OrderedMap as OrderedMap
-import qualified Language.GraphQL.Execute.Transform as Transform
-import Language.GraphQL.Error
-    ( Error(..)
-    , ResolverException
-    , Response
-    , ResponseEventStream
-    , runCollectErrs
-    )
-import qualified Language.GraphQL.Type.Definition as Definition
-import qualified Language.GraphQL.Type as Type
-import qualified Language.GraphQL.Type.Out as Out
-import Language.GraphQL.Type.Schema
-
-subscribe :: (MonadCatch m, Serialize a)
-    => HashMap Full.Name (Type m)
-    -> Out.ObjectType m
-    -> Full.Location
-    -> Seq (Transform.Selection m)
-    -> m (Either Error (ResponseEventStream m a))
-subscribe types' objectType objectLocation fields = do
-    sourceStream <-
-        createSourceEventStream types' objectType objectLocation fields
-    let traverser =
-            mapSourceToResponseEvent types' objectType objectLocation fields
-    traverse traverser sourceStream
-
-mapSourceToResponseEvent :: (MonadCatch m, Serialize a)
-    => HashMap Full.Name (Type m)
-    -> Out.ObjectType m
-    -> Full.Location
-    -> Seq (Transform.Selection m)
-    -> Out.SourceEventStream m
-    -> m (ResponseEventStream m a)
-mapSourceToResponseEvent types' subscriptionType objectLocation fields sourceStream
-    = pure
-    $ sourceStream
-    .| mapMC (executeSubscriptionEvent types' subscriptionType objectLocation fields)
-
-createSourceEventStream :: MonadCatch m
-    => HashMap Full.Name (Type m)
-    -> Out.ObjectType m
-    -> Full.Location
-    -> Seq (Transform.Selection m)
-    -> m (Either Error (Out.SourceEventStream m))
-createSourceEventStream _types subscriptionType objectLocation fields
-    | [fieldGroup] <- OrderedMap.elems groupedFieldSet
-    , Transform.Field _ fieldName arguments' _ errorLocation <- NonEmpty.head fieldGroup
-    , Out.ObjectType _ _ _ fieldTypes <- subscriptionType
-    , resolverT <- fieldTypes HashMap.! fieldName
-    , Out.EventStreamResolver fieldDefinition _ resolver <- resolverT
-    , Out.Field _ _fieldType argumentDefinitions <- fieldDefinition =
-        case coerceArgumentValues argumentDefinitions arguments' of
-            Left _ -> pure
-                $ Left
-                $ Error "Argument coercion failed." [errorLocation] []
-            Right  argumentValues -> left (singleError [errorLocation])
-                <$> resolveFieldEventStream Type.Null argumentValues resolver
-    | otherwise = pure
-        $ Left
-        $ Error "Subscription contains more than one field." [objectLocation] []
-  where
-    groupedFieldSet = collectFields subscriptionType fields
-
-resolveFieldEventStream :: MonadCatch m
-    => Type.Value
-    -> Type.Subs
-    -> Out.Subscribe m
-    -> m (Either String (Out.SourceEventStream m))
-resolveFieldEventStream result args resolver =
-    catch (Right <$> runReaderT resolver context) handleEventStreamError
-  where
-    handleEventStreamError :: MonadCatch m
-        => ResolverException
-        -> m (Either String (Out.SourceEventStream m))
-    handleEventStreamError = pure . Left . displayException
-    context = Type.Context
-        { Type.arguments = Type.Arguments args
-        , Type.values = result
-        }
-
-executeSubscriptionEvent :: (MonadCatch m, Serialize a)
-    => HashMap Full.Name (Type m)
-    -> Out.ObjectType m
-    -> Full.Location
-    -> Seq (Transform.Selection m)
-    -> Definition.Value
-    -> m (Response a)
-executeSubscriptionEvent types' objectType objectLocation fields initialValue
-    = runCollectErrs types'
-    $ executeSelectionSet initialValue objectType objectLocation fields

src/Language/GraphQL/Execute/Transform.hs

@@ -6,7 +6,7 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
-{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE NamedFieldPuns #-}
 
 -- | After the document is parsed, before getting executed, the AST is
 -- transformed into a similar, simpler AST. Performed transformations include:
@@ -21,65 +21,87 @@
 -- This module is also responsible for smaller rewrites that touch only parts of
 -- the original AST.
 module Language.GraphQL.Execute.Transform
-    ( Document(..)
-    , Field(..)
+    ( Field(..)
     , Fragment(..)
     , Input(..)
     , Operation(..)
-    , QueryError(..)
+    , Replacement(..)
     , Selection(..)
+    , TransformT(..)
     , document
+    , transform
     ) where
 
-import Control.Monad (foldM, unless)
-import Control.Monad.Trans.Class (lift)
-import Control.Monad.Trans.State (State, evalStateT, gets, modify)
-import Data.Foldable (find)
-import Data.Functor.Identity (Identity(..))
+import Control.Monad (foldM)
+import Control.Monad.Catch (MonadCatch(..), MonadThrow(..))
+import Control.Monad.Trans.Class (MonadTrans(..))
+import Control.Monad.Trans.Reader (ReaderT(..), local)
+import qualified Control.Monad.Trans.Reader as Reader
+import Data.Bifunctor (first)
+import Data.Functor ((<&>))
 import Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as HashMap
+import Data.HashSet (HashSet)
+import qualified Data.HashSet as HashSet
 import Data.Int (Int32)
-import Data.Maybe (fromMaybe)
-import Data.List.NonEmpty (NonEmpty(..))
+import Data.List (intercalate)
 import qualified Data.List.NonEmpty as NonEmpty
-import Data.Sequence (Seq, (<|), (><))
+import Data.Maybe (fromMaybe, isJust)
+import Data.Sequence (Seq, (><))
+import qualified Data.Sequence as Seq
 import Data.Text (Text)
 import qualified Data.Text as Text
-import qualified Language.GraphQL.AST as Full
-import Language.GraphQL.AST (Name)
-import qualified Language.GraphQL.Execute.Coerce as Coerce
-import qualified Language.GraphQL.Type.Definition as Definition
+import qualified Language.GraphQL.AST.Document as Full
+import Language.GraphQL.Type.Schema (Type)
 import qualified Language.GraphQL.Type as Type
+import qualified Language.GraphQL.Type.Definition as Definition
 import qualified Language.GraphQL.Type.Internal as Type
-import qualified Language.GraphQL.Type.Out as Out
-import qualified Language.GraphQL.Type.Schema as Schema
+import Numeric (showFloat)
 
 -- | Associates a fragment name with a list of 'Field's.
 data Replacement m = Replacement
-    { fragments :: HashMap Full.Name (Fragment m)
-    , fragmentDefinitions :: FragmentDefinitions
-    , variableValues :: Type.Subs
-    , types :: HashMap Full.Name (Schema.Type m)
+    { variableValues :: Type.Subs
+    , fragmentDefinitions :: HashMap Full.Name Full.FragmentDefinition
+    , visitedFragments :: HashSet Full.Name
+    , types :: HashMap Full.Name (Type m)
     }
 
-type FragmentDefinitions = HashMap Full.Name Full.FragmentDefinition
+newtype TransformT m a = TransformT
+    { runTransformT :: ReaderT (Replacement m) m a
+    }
 
--- | Represents fragments and inline fragments.
-data Fragment m
-    = Fragment (Type.CompositeType m) (Seq (Selection m))
+instance Functor m => Functor (TransformT m) where
+    fmap f = TransformT . fmap f . runTransformT
 
--- | Single selection element.
-data Selection m
-    = SelectionFragment (Fragment m)
-    | SelectionField (Field m)
+instance Applicative m => Applicative (TransformT m) where
+    pure = TransformT . pure
+    TransformT f <*> TransformT x = TransformT $ f <*> x
+
+instance Monad m => Monad (TransformT m) where
+    TransformT x >>= f = TransformT $ x >>= runTransformT . f
+
+instance MonadTrans TransformT where
+    lift = TransformT . lift
+
+instance MonadThrow m => MonadThrow (TransformT m) where
+    throwM = lift . throwM
+
+instance MonadCatch m => MonadCatch (TransformT m) where
+  catch (TransformT stack) handler =
+      TransformT $ catch stack $ runTransformT . handler
+
+asks :: Monad m => forall a. (Replacement m -> a) -> TransformT m a
+asks = TransformT . Reader.asks
 
 -- | GraphQL has 3 operation types: queries, mutations and subscribtions.
 data Operation m
-    = Query (Maybe Text) (Seq (Selection m)) Full.Location
-    | Mutation (Maybe Text) (Seq (Selection m)) Full.Location
-    | Subscription (Maybe Text) (Seq (Selection m)) Full.Location
+    = Operation Full.OperationType (Seq (Selection m)) Full.Location
+
+-- | Field or inlined fragment.
+data Selection m
+    = FieldSelection (Field m)
+    | FragmentSelection (Fragment m)
 
--- | Single GraphQL field.
 data Field m = Field
     (Maybe Full.Name)
     Full.Name
@@ -87,339 +109,217 @@ data Field m = Field
     (Seq (Selection m))
     Full.Location
 
--- | Contains the operation to be executed along with its root type.
-data Document m = Document
-    (HashMap Full.Name (Schema.Type m)) (Out.ObjectType m) (Operation m)
-
-data OperationDefinition = OperationDefinition
-    Full.OperationType
-    (Maybe Full.Name)
-    [Full.VariableDefinition]
-    [Full.Directive]
-    Full.SelectionSet
-    Full.Location
-
--- | Query error types.
-data QueryError
-    = OperationNotFound Text
-    | OperationNameRequired
-    | CoercionError
-    | EmptyDocument
-    | UnsupportedRootOperation
-
-instance Show QueryError where
-    show (OperationNotFound operationName) = unwords
-        ["Operation", Text.unpack operationName, "couldn't be found in the document."]
-    show OperationNameRequired = "Missing operation name."
-    show CoercionError = "Coercion error."
-    show EmptyDocument =
-        "The document doesn't contain any executable operations."
-    show UnsupportedRootOperation =
-        "Root operation type couldn't be found in the schema."
+data Fragment m = Fragment
+    (Type.CompositeType m) (Seq (Selection m)) Full.Location
 
 data Input
-    = Int Int32
+    = Variable Type.Value
+    | Int Int32
     | Float Double
     | String Text
     | Boolean Bool
     | Null
-    | Enum Name
-    | List [Type.Value]
-    | Object (HashMap Name Input)
-    | Variable Type.Value
-    deriving (Eq, Show)
+    | Enum Full.Name
+    | List [Input]
+    | Object (HashMap Full.Name Input)
+    deriving Eq
 
-getOperation
-    :: Maybe Full.Name
-    -> NonEmpty OperationDefinition
-    -> Either QueryError OperationDefinition
-getOperation Nothing (operation' :| []) = pure operation'
-getOperation Nothing _ = Left OperationNameRequired
-getOperation (Just operationName) operations
-    | Just operation' <- find matchingName operations = pure operation'
-    | otherwise = Left $ OperationNotFound operationName
+instance Show Input where
+    showList = mappend . showList'
+      where
+        showList' list = "[" ++ intercalate ", " (show <$> list) ++ "]"
+    show (Int integer) = show integer
+    show (Float float') = showFloat float' mempty
+    show (String text) = "\"" <> Text.foldr (mappend . Full.escape) "\"" text
+    show (Boolean boolean') = show boolean'
+    show Null = "null"
+    show (Enum name) = Text.unpack name
+    show (List list) = show list
+    show (Object fields) = unwords
+        [ "{"
+        , intercalate ", " (HashMap.foldrWithKey showObject [] fields)
+        , "}"
+        ]
+      where
+        showObject key value accumulator =
+            concat [Text.unpack key, ": ", show value] : accumulator
+    show variableValue = show variableValue
+
+-- | Extracts operations and fragment definitions of the document.
+document :: Full.Document
+    -> ([Full.OperationDefinition], HashMap Full.Name Full.FragmentDefinition)
+document = foldr filterOperation ([], HashMap.empty)
   where
-    matchingName (OperationDefinition _ name _ _ _ _) =
-        name == Just operationName
-
-coerceVariableValues :: Coerce.VariableValue a
-    => forall m
-    . HashMap Full.Name (Schema.Type m)
-    -> OperationDefinition
-    -> HashMap.HashMap Full.Name a
-    -> Either QueryError Type.Subs
-coerceVariableValues types operationDefinition variableValues =
-    let OperationDefinition _ _ variableDefinitions _ _ _ = operationDefinition
-     in maybe (Left CoercionError) Right
-        $ foldr forEach (Just HashMap.empty) variableDefinitions
-  where
-    forEach variableDefinition coercedValues = do
-        let Full.VariableDefinition variableName variableTypeName defaultValue _ =
-                variableDefinition
-        let defaultValue' = constValue . Full.node <$> defaultValue
-        variableType <- Type.lookupInputType variableTypeName types
-
-        Coerce.matchFieldValues
-            coerceVariableValue'
-            variableValues
-            variableName
-            variableType
-            defaultValue'
-            coercedValues
-    coerceVariableValue' variableType value'
-        = Coerce.coerceVariableValue variableType value'
-        >>= Coerce.coerceInputLiteral variableType
-
-constValue :: Full.ConstValue -> Type.Value
-constValue (Full.ConstInt i) = Type.Int i
-constValue (Full.ConstFloat f) = Type.Float f
-constValue (Full.ConstString x) = Type.String x
-constValue (Full.ConstBoolean b) = Type.Boolean b
-constValue Full.ConstNull = Type.Null
-constValue (Full.ConstEnum e) = Type.Enum e
-constValue (Full.ConstList list) = Type.List $ constValue . Full.node <$> list
-constValue (Full.ConstObject o) =
-    Type.Object $ HashMap.fromList $ constObjectField <$> o
-  where
-    constObjectField Full.ObjectField{value = value', ..} =
-        (name, constValue $ Full.node value')
+    filterOperation (Full.ExecutableDefinition executableDefinition) accumulator
+        | Full.DefinitionOperation operationDefinition' <- executableDefinition =
+            first (operationDefinition' :) accumulator
+        | Full.DefinitionFragment fragmentDefinition <- executableDefinition
+        , Full.FragmentDefinition fragmentName _ _ _ _ <- fragmentDefinition =
+            HashMap.insert fragmentName fragmentDefinition <$> accumulator
+    filterOperation _ accumulator = accumulator -- Type system definitions.
 
 -- | Rewrites the original syntax tree into an intermediate representation used
--- for query execution.
-document :: Coerce.VariableValue a
-    => forall m
-    . Type.Schema m
-    -> Maybe Full.Name
+-- for the query execution.
+transform :: Monad m => Full.OperationDefinition -> TransformT m (Operation m)
+transform (Full.OperationDefinition operationType _ _ _ selectionSet' operationLocation) = do
+    transformedSelections <- selectionSet selectionSet'
+    pure $ Operation operationType transformedSelections operationLocation
+transform (Full.SelectionSet selectionSet' operationLocation) = do
+    transformedSelections <- selectionSet selectionSet'
+    pure $ Operation Full.Query transformedSelections operationLocation
+
+selectionSet :: Monad m => Full.SelectionSet -> TransformT m (Seq (Selection m))
+selectionSet = selectionSetOpt . NonEmpty.toList
+
+selectionSetOpt :: Monad m => Full.SelectionSetOpt -> TransformT m (Seq (Selection m))
+selectionSetOpt = foldM go Seq.empty
+  where
+    go accumulatedSelections currentSelection =
+        selection currentSelection <&> (accumulatedSelections ><)
+
+selection :: Monad m => Full.Selection -> TransformT m (Seq (Selection m))
+selection (Full.FieldSelection field') =
+    maybeToSelectionSet FieldSelection $ field field'
+selection (Full.FragmentSpreadSelection fragmentSpread') =
+    maybeToSelectionSet FragmentSelection $ fragmentSpread fragmentSpread'
+selection (Full.InlineFragmentSelection inlineFragment') =
+    either id (pure . FragmentSelection) <$> inlineFragment inlineFragment'
+
+maybeToSelectionSet :: Monad m
+    => forall a
+    . (a -> Selection m)
+    -> TransformT m (Maybe a)
+    -> TransformT m (Seq (Selection m))
+maybeToSelectionSet selectionType = fmap (maybe Seq.empty $ pure . selectionType)
+
+directives :: Monad m => [Full.Directive] -> TransformT m (Maybe [Definition.Directive])
+directives = fmap Type.selection . traverse directive
+
+inlineFragment :: Monad m
+    => Full.InlineFragment
+    -> TransformT m (Either (Seq (Selection m)) (Fragment m))
+inlineFragment (Full.InlineFragment maybeCondition directives' selectionSet' location)
+    | Just typeCondition <- maybeCondition = do
+        transformedSelections <- selectionSet selectionSet'
+        transformedDirectives <- directives directives'
+        maybeFragmentType <- asks
+            $ Type.lookupTypeCondition typeCondition
+            . types
+        pure $ case transformedDirectives >> maybeFragmentType of
+            Just fragmentType -> Right
+                $ Fragment fragmentType transformedSelections location
+            Nothing -> Left Seq.empty
+    | otherwise = do
+        transformedSelections <- selectionSet selectionSet'
+        transformedDirectives <- directives directives'
+        pure $ if isJust transformedDirectives
+            then Left transformedSelections
+            else Left Seq.empty
+
+fragmentSpread :: Monad m => Full.FragmentSpread -> TransformT m (Maybe (Fragment m))
+fragmentSpread (Full.FragmentSpread spreadName directives' location) = do
+    transformedDirectives <- directives directives'
+    visitedFragment <- asks $ HashSet.member spreadName . visitedFragments
+    possibleFragmentDefinition <- asks
+        $ HashMap.lookup spreadName
+        . fragmentDefinitions
+    case transformedDirectives >> possibleFragmentDefinition of
+        Just (Full.FragmentDefinition _ typeCondition _ selections _)
+            | visitedFragment -> pure Nothing
+            | otherwise -> do
+                fragmentType <- asks
+                    $ Type.lookupTypeCondition typeCondition
+                    . types
+                traverse (traverseSelections selections) fragmentType
+        Nothing -> pure Nothing
+  where
+    traverseSelections selections typeCondition = do
+        transformedSelections <- TransformT
+            $ local fragmentInserter
+            $ runTransformT
+            $ selectionSet selections
+        pure $ Fragment typeCondition transformedSelections location
+    fragmentInserter replacement@Replacement{ visitedFragments } = replacement
+        { visitedFragments = HashSet.insert spreadName visitedFragments }
+
+field :: Monad m => Full.Field -> TransformT m (Maybe (Field m))
+field (Full.Field alias' name' arguments' directives' selectionSet' location') = do
+    transformedSelections <- selectionSetOpt selectionSet'
+    transformedDirectives <- directives directives'
+    transformedArguments <- arguments arguments'
+    let transformedField = Field
+            alias'
+            name'
+            transformedArguments
+            transformedSelections
+            location'
+    pure $ transformedDirectives >> pure transformedField
+
+arguments :: Monad m => [Full.Argument] -> TransformT m (HashMap Full.Name (Full.Node Input))
+arguments = foldM go HashMap.empty
+  where
+    go accumulator (Full.Argument name' valueNode argumentLocation) = do
+        let replaceLocation = flip Full.Node argumentLocation . Full.node
+        argumentValue <- fmap replaceLocation <$> node valueNode
+        pure $ insertIfGiven name' argumentValue accumulator
+
+directive :: Monad m => Full.Directive -> TransformT m Definition.Directive
+directive (Full.Directive name' arguments' _)
+    = Definition.Directive name'
+    . Type.Arguments
+    <$> foldM go HashMap.empty arguments'
+  where
+    go accumulator (Full.Argument argumentName Full.Node{ node = node' } _) = do
+        transformedValue <- directiveValue node'
+        pure $ HashMap.insert argumentName transformedValue accumulator
+
+directiveValue :: Monad m => Full.Value -> TransformT m Type.Value
+directiveValue = \case
+    (Full.Variable name') -> asks
+        $ HashMap.lookupDefault Type.Null name'
+        . variableValues
+    (Full.Int integer) -> pure $ Type.Int integer
+    (Full.Float double) -> pure $ Type.Float double
+    (Full.String string) -> pure $ Type.String string
+    (Full.Boolean boolean) -> pure $ Type.Boolean boolean
+    Full.Null -> pure Type.Null
+    (Full.Enum enum) -> pure $ Type.Enum enum
+    (Full.List list) -> Type.List <$> traverse directiveNode list
+    (Full.Object objectFields) ->
+        Type.Object <$> foldM objectField HashMap.empty objectFields
+  where
+    directiveNode Full.Node{ node = node'} = directiveValue node'
+    objectField accumulator Full.ObjectField{ name, value } = do
+        transformedValue <- directiveNode value
+        pure $ HashMap.insert name transformedValue accumulator
+
+input :: Monad m => Full.Value -> TransformT m (Maybe Input)
+input (Full.Variable name') =
+    asks (HashMap.lookup name' . variableValues) <&> fmap Variable
+input (Full.Int integer) = pure $ Just $ Int integer
+input (Full.Float double) = pure $ Just $ Float double
+input (Full.String string) = pure $ Just $ String string
+input (Full.Boolean boolean) = pure $ Just $ Boolean boolean
+input Full.Null = pure $ Just Null
+input (Full.Enum enum) = pure $ Just $ Enum enum
+input (Full.List list) = Just . List
+    <$> traverse (fmap (fromMaybe Null) . input . Full.node) list
+input (Full.Object objectFields) = Just . Object
+    <$> foldM objectField HashMap.empty objectFields
+  where
+    objectField accumulator Full.ObjectField{..} = do
+        objectFieldValue <- fmap Full.node <$> node value
+        pure $ insertIfGiven name objectFieldValue accumulator
+
+insertIfGiven :: forall a
+    . Full.Name
+    -> Maybe a
     -> HashMap Full.Name a
-    -> Full.Document
-    -> Either QueryError (Document m)
-document schema operationName subs ast = do
-    let referencedTypes = Schema.types schema
+    -> HashMap Full.Name a
+insertIfGiven name (Just v) = HashMap.insert name v
+insertIfGiven _ _ = id
 
-    (operations, fragmentTable) <- defragment ast
-    chosenOperation <- getOperation operationName operations
-    coercedValues <- coerceVariableValues referencedTypes chosenOperation subs
+node :: Monad m => Full.Node Full.Value -> TransformT m (Maybe (Full.Node Input))
+node Full.Node{node = node', ..} =
+    traverse Full.Node <$> input node' <*> pure location
 
-    let replacement = Replacement
-            { fragments = HashMap.empty
-            , fragmentDefinitions = fragmentTable
-            , variableValues = coercedValues
-            , types = referencedTypes
-            }
-    case chosenOperation of
-        OperationDefinition Full.Query _ _ _ _ _ ->
-            pure $ Document referencedTypes (Schema.query schema)
-                $ operation chosenOperation replacement
-        OperationDefinition Full.Mutation _ _ _ _ _
-            | Just mutationType <- Schema.mutation schema ->
-                pure $ Document referencedTypes mutationType
-                    $ operation chosenOperation replacement
-        OperationDefinition Full.Subscription _ _ _ _ _
-            | Just subscriptionType <- Schema.subscription schema ->
-                pure $ Document referencedTypes subscriptionType
-                    $ operation chosenOperation replacement
-        _ -> Left UnsupportedRootOperation
-
-defragment
-    :: Full.Document
-    -> Either QueryError (NonEmpty OperationDefinition, FragmentDefinitions)
-defragment ast =
-    let (operations, fragmentTable) = foldr defragment' ([], HashMap.empty) ast
-        nonEmptyOperations = NonEmpty.nonEmpty operations
-        emptyDocument = Left EmptyDocument
-     in (, fragmentTable) <$> maybe emptyDocument Right nonEmptyOperations
-  where
-    defragment' definition (operations, fragments')
-        | (Full.ExecutableDefinition executable) <- definition
-        , (Full.DefinitionOperation operation') <- executable =
-            (transform operation' : operations, fragments')
-        | (Full.ExecutableDefinition executable) <- definition
-        , (Full.DefinitionFragment fragment) <- executable
-        , (Full.FragmentDefinition name _ _ _ _) <- fragment =
-            (operations, HashMap.insert name fragment fragments')
-    defragment' _ acc = acc
-    transform = \case
-        Full.OperationDefinition type' name variables directives' selections location ->
-            OperationDefinition type' name variables directives' selections location
-        Full.SelectionSet selectionSet location ->
-            OperationDefinition Full.Query Nothing mempty mempty selectionSet location
-
--- * Operation
-
-operation :: OperationDefinition -> Replacement m -> Operation m
-operation operationDefinition replacement
-    = runIdentity
-    $ evalStateT (collectFragments >> transform operationDefinition) replacement
-  where
-    transform (OperationDefinition Full.Query name _ _ sels location) =
-        flip (Query name) location <$> appendSelection sels
-    transform (OperationDefinition Full.Mutation name _ _ sels location) =
-        flip (Mutation name) location <$> appendSelection sels
-    transform (OperationDefinition Full.Subscription name _ _ sels location) =
-        flip (Subscription name) location <$> appendSelection sels
-
--- * Selection
-
-selection
-    :: Full.Selection
-    ->  State (Replacement m) (Either (Seq (Selection m)) (Selection m))
-selection (Full.FieldSelection fieldSelection) =
-    maybe (Left mempty) (Right . SelectionField) <$> field fieldSelection
-selection (Full.FragmentSpreadSelection fragmentSelection)
-    = maybe (Left mempty) (Right . SelectionFragment)
-    <$> fragmentSpread fragmentSelection
-selection (Full.InlineFragmentSelection fragmentSelection) =
-    inlineFragment fragmentSelection
-
-field :: Full.Field ->  State (Replacement m) (Maybe (Field m))
-field (Full.Field alias name arguments' directives' selections location) = do
-    fieldArguments <- foldM go HashMap.empty arguments'
-    fieldSelections <- appendSelection selections
-    fieldDirectives <- Definition.selection <$> directives directives'
-    let field' = Field alias name fieldArguments fieldSelections location
-    pure $ field' <$ fieldDirectives
-  where
-    go arguments (Full.Argument name' (Full.Node value' _) location') = do
-        objectFieldValue <-  input value'
-        case objectFieldValue of
-            Just fieldValue ->
-                let argumentNode = Full.Node fieldValue location'
-                 in pure $ HashMap.insert name' argumentNode arguments
-            Nothing -> pure arguments
-
-fragmentSpread
-    :: Full.FragmentSpread
-    -> State (Replacement m) (Maybe (Fragment m))
-fragmentSpread (Full.FragmentSpread name directives' _) = do
-    spreadDirectives <- Definition.selection <$> directives directives'
-    fragments' <- gets fragments
-
-    fragmentDefinitions' <- gets fragmentDefinitions
-    case HashMap.lookup name fragments' of
-        Just definition -> lift $ pure $ definition <$ spreadDirectives
-        Nothing
-            | Just definition <- HashMap.lookup name fragmentDefinitions' -> do
-                fragDef <- fragmentDefinition definition
-                case fragDef of
-                    Just fragment -> lift $ pure $ fragment <$ spreadDirectives
-                    _ -> lift $ pure  Nothing
-            | otherwise -> lift $ pure  Nothing
-
-inlineFragment
-    :: Full.InlineFragment
-    ->  State (Replacement m) (Either (Seq (Selection m)) (Selection m))
-inlineFragment (Full.InlineFragment type' directives' selections _) = do
-    fragmentDirectives <- Definition.selection <$> directives directives'
-    case fragmentDirectives of
-        Nothing -> pure $ Left mempty
-        _ -> do
-            fragmentSelectionSet <- appendSelection selections
-
-            case type' of
-                Nothing -> pure $ Left fragmentSelectionSet
-                Just typeName -> do
-                    types' <- gets types
-                    case Type.lookupTypeCondition typeName types' of
-                        Just typeCondition -> pure $
-                            selectionFragment typeCondition fragmentSelectionSet
-                        Nothing -> pure $ Left mempty
-  where
-    selectionFragment typeName = Right
-        . SelectionFragment
-        . Fragment typeName
-
-appendSelection :: Traversable t
-    => t Full.Selection
-    ->  State (Replacement m) (Seq (Selection m))
-appendSelection = foldM go mempty
-  where
-    go acc sel = append acc <$> selection sel
-    append acc (Left list) = list >< acc
-    append acc (Right one) = one <| acc
-
-directives :: [Full.Directive] ->  State (Replacement m) [Definition.Directive]
-directives = traverse directive
-  where
-    directive (Full.Directive directiveName directiveArguments _)
-        = Definition.Directive directiveName . Type.Arguments
-        <$> foldM go HashMap.empty directiveArguments
-    go arguments (Full.Argument name (Full.Node value' _) _) = do
-        substitutedValue <- value value'
-        return $ HashMap.insert name substitutedValue arguments
-
--- * Fragment replacement
-
--- | Extract fragment definitions into a single 'HashMap'.
-collectFragments ::  State (Replacement m) ()
-collectFragments = do
-    fragDefs <- gets fragmentDefinitions
-    let nextValue = head $ HashMap.elems fragDefs
-    unless (HashMap.null fragDefs) $ do
-        _ <- fragmentDefinition nextValue
-        collectFragments
-
-fragmentDefinition
-    :: Full.FragmentDefinition
-    ->  State (Replacement m) (Maybe (Fragment m))
-fragmentDefinition (Full.FragmentDefinition name type' _ selections _) = do
-    modify deleteFragmentDefinition
-    fragmentSelection <- appendSelection selections
-    types' <- gets types
-
-    case Type.lookupTypeCondition type' types' of
-        Just compositeType -> do
-            let newValue = Fragment compositeType fragmentSelection
-            modify $ insertFragment newValue
-            lift $ pure $ Just newValue
-        _ -> lift $ pure Nothing
-  where
-    deleteFragmentDefinition replacement@Replacement{..} =
-        let newDefinitions = HashMap.delete name fragmentDefinitions
-         in replacement{ fragmentDefinitions = newDefinitions }
-    insertFragment newValue replacement@Replacement{..} =
-        let newFragments = HashMap.insert name newValue fragments
-         in replacement{ fragments = newFragments }
-
-value :: forall m. Full.Value -> State (Replacement m) Type.Value
-value (Full.Variable name) =
-    gets (fromMaybe Type.Null . HashMap.lookup name . variableValues)
-value (Full.Int int) = pure $ Type.Int int
-value (Full.Float float) = pure $ Type.Float float
-value (Full.String string) = pure $ Type.String string
-value (Full.Boolean boolean) = pure $ Type.Boolean boolean
-value Full.Null = pure Type.Null
-value (Full.Enum enum) = pure $ Type.Enum enum
-value (Full.List list) = Type.List <$> traverse (value . Full.node) list
-value (Full.Object object) =
-    Type.Object . HashMap.fromList <$> traverse objectField object
-  where
-    objectField Full.ObjectField{value = value', ..} =
-        (name,) <$> value (Full.node value')
-
-input :: forall m. Full.Value -> State (Replacement m) (Maybe Input)
-input (Full.Variable name) =
-    gets (fmap Variable . HashMap.lookup name . variableValues)
-input (Full.Int int) = pure $ pure $ Int int
-input (Full.Float float) = pure $ pure $ Float float
-input (Full.String string) = pure $ pure $ String string
-input (Full.Boolean boolean) = pure $ pure $ Boolean boolean
-input Full.Null = pure $ pure Null
-input (Full.Enum enum) = pure $ pure $ Enum enum
-input (Full.List list) = pure . List <$> traverse (value . Full.node) list
-input (Full.Object object) = do
-    objectFields <- foldM objectField HashMap.empty object
-    pure $ pure $ Object objectFields
-  where
-    objectField resultMap Full.ObjectField{value = value', ..} =
-        inputField resultMap name $ Full.node value'
-
-inputField :: forall m
-    . HashMap Full.Name Input
-    -> Full.Name
-    -> Full.Value
-    -> State (Replacement m) (HashMap Full.Name Input)
-inputField resultMap name value' = do
-    objectFieldValue <-  input value'
-    case objectFieldValue of
-        Just fieldValue -> pure $ HashMap.insert name fieldValue resultMap
-        Nothing -> pure resultMap

src/Language/GraphQL/TH.hs

@@ -0,0 +1,38 @@
+{- 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/. -}
+
+-- | Template Haskell helpers.
+module Language.GraphQL.TH
+    ( gql
+    ) where
+
+import Language.Haskell.TH.Quote (QuasiQuoter(..))
+import Language.Haskell.TH (Exp(..), Lit(..))
+
+stripIndentation :: String -> String
+stripIndentation code = reverse
+    $ dropNewlines
+    $ reverse
+    $ unlines
+    $ indent spaces <$> lines withoutLeadingNewlines
+  where
+    indent 0 xs = xs
+    indent count (' ' : xs) = indent (count - 1) xs
+    indent _ xs = xs
+    withoutLeadingNewlines = dropNewlines code
+    dropNewlines = dropWhile (== '\n')
+    spaces = length $ takeWhile (== ' ') withoutLeadingNewlines
+
+-- | Removes leading and trailing newlines. Indentation of the first line is
+-- removed from each line of the string.
+gql :: QuasiQuoter
+gql = QuasiQuoter
+    { quoteExp = pure . LitE . StringL . stripIndentation
+    , quotePat = const
+        $ fail "Illegal gql QuasiQuote (allowed as expression only, used as a pattern)"
+    , quoteType = const
+        $ fail "Illegal gql QuasiQuote (allowed as expression only, used as a type)"
+    , quoteDec = const
+        $ fail "Illegal gql QuasiQuote (allowed as expression only, used as a declaration)"
+    }

src/Language/GraphQL/Type/Definition.hs

@@ -1,4 +1,9 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE Safe #-}
 
 -- | Types that can be used as both input and output types.
 module Language.GraphQL.Type.Definition
@@ -20,10 +25,12 @@ module Language.GraphQL.Type.Definition
 import Data.Int (Int32)
 import Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as HashMap
+import Data.List (intercalate)
 import Data.String (IsString(..))
 import Data.Text (Text)
 import qualified Data.Text as Text
-import Language.GraphQL.AST (Name)
+import Language.GraphQL.AST (Name, escape)
+import Numeric (showFloat)
 import Prelude hiding (id)
 
 -- | Represents accordingly typed GraphQL values.
@@ -36,7 +43,27 @@ data Value
     | Enum Name
     | List [Value] -- ^ Arbitrary nested list.
     | Object (HashMap Name Value)
-    deriving (Eq, Show)
+    deriving Eq
+
+instance Show Value where
+    showList = mappend . showList'
+      where
+        showList' list = "[" ++ intercalate ", " (show <$> list) ++ "]"
+    show (Int integer) = show integer
+    show (Float float') = showFloat float' mempty
+    show (String text) = "\"" <> Text.foldr (mappend . escape) "\"" text
+    show (Boolean boolean') = show boolean'
+    show Null = "null"
+    show (Enum name) = Text.unpack name
+    show (List list) = show list
+    show (Object fields) = unwords
+        [ "{"
+        , intercalate ", " (HashMap.foldrWithKey showObject [] fields)
+        , "}"
+        ]
+      where
+        showObject key value accumulator =
+            concat [Text.unpack key, ": ", show value] : accumulator
 
 instance IsString Value where
     fromString = String . fromString

src/Language/GraphQL/Type/In.hs

@@ -3,6 +3,7 @@
    obtain one at https://mozilla.org/MPL/2.0/. -}
 
 {-# LANGUAGE PatternSynonyms #-}
+{-# LANGUAGE Safe #-}
 {-# LANGUAGE ViewPatterns #-}
 
 -- | Input types and values.

tests/Language/GraphQL/AST/EncoderSpec.hs

@@ -6,10 +6,10 @@ module Language.GraphQL.AST.EncoderSpec
 
 import qualified Language.GraphQL.AST.Document as Full
 import Language.GraphQL.AST.Encoder
+import Language.GraphQL.TH
 import Test.Hspec (Spec, context, describe, it, shouldBe, shouldStartWith, shouldEndWith, shouldNotContain)
 import Test.QuickCheck (choose, oneof, forAll)
-import Text.RawString.QQ (r)
-import Data.Text.Lazy (cons, toStrict, unpack)
+import qualified Data.Text.Lazy as Text.Lazy
 
 spec :: Spec
 spec = do
@@ -48,23 +48,32 @@ spec = do
             it "uses strings for short string values" $
                 value pretty (Full.String "Short text") `shouldBe` "\"Short text\""
             it "uses block strings for text with new lines, with newline symbol" $
-                value pretty (Full.String "Line 1\nLine 2")
-                    `shouldBe` [r|"""
-  Line 1
-  Line 2
-"""|]
+                let expected = [gql|
+                  """
+                    Line 1
+                    Line 2
+                  """
+                |]
+                    actual = value pretty $ Full.String "Line 1\nLine 2"
+                 in actual `shouldBe` expected
             it "uses block strings for text with new lines, with CR symbol" $
-                value pretty (Full.String "Line 1\rLine 2")
-                    `shouldBe` [r|"""
-  Line 1
-  Line 2
-"""|]
+                let expected = [gql|
+                  """
+                    Line 1
+                    Line 2
+                  """
+                |]
+                    actual = value pretty $ Full.String "Line 1\rLine 2"
+                 in actual `shouldBe` expected
             it "uses block strings for text with new lines, with CR symbol followed by newline" $
-                value pretty (Full.String "Line 1\r\nLine 2")
-                    `shouldBe` [r|"""
-  Line 1
-  Line 2
-"""|]
+                let expected = [gql|
+                  """
+                    Line 1
+                    Line 2
+                  """
+                |]
+                    actual = value pretty $ Full.String "Line 1\r\nLine 2"
+                 in actual `shouldBe` expected
             it "encodes as one line string if has escaped symbols" $ do
                 let
                   genNotAllowedSymbol = oneof
@@ -76,48 +85,74 @@ spec = do
 
                 forAll genNotAllowedSymbol $ \x -> do
                     let
-                      rawValue = "Short \n" <> cons x "text"
-                      encoded = value pretty (Full.String $ toStrict rawValue)
-                    shouldStartWith (unpack encoded) "\""
-                    shouldEndWith (unpack encoded) "\""
-                    shouldNotContain (unpack encoded) "\"\"\""
+                      rawValue = "Short \n" <> Text.Lazy.cons x "text"
+                      encoded = value pretty
+                          $ Full.String $ Text.Lazy.toStrict rawValue
+                    shouldStartWith (Text.Lazy.unpack encoded) "\""
+                    shouldEndWith (Text.Lazy.unpack encoded) "\""
+                    shouldNotContain (Text.Lazy.unpack encoded) "\"\"\""
 
-            it "Hello world" $ value pretty (Full.String "Hello,\n  World!\n\nYours,\n  GraphQL.")
-              `shouldBe` [r|"""
-  Hello,
-    World!
+            it "Hello world" $
+                let actual = value pretty
+                        $ Full.String "Hello,\n  World!\n\nYours,\n  GraphQL."
+                    expected = [gql|
+                      """
+                        Hello,
+                          World!
 
-  Yours,
-    GraphQL.
-"""|]
+                        Yours,
+                          GraphQL.
+                      """
+                    |]
+                  in actual `shouldBe` expected
 
-            it "has only newlines" $ value pretty (Full.String "\n") `shouldBe` [r|"""
+            it "has only newlines" $
+                let actual = value pretty $ Full.String "\n"
+                    expected = [gql|
+                      """
 
 
-"""|]
+                      """
+                    |]
+                 in actual `shouldBe` expected
             it "has newlines and one symbol at the begining" $
-              value pretty (Full.String "a\n\n") `shouldBe` [r|"""
-  a
+                let actual = value pretty $ Full.String "a\n\n"
+                    expected = [gql|
+                      """
+                        a
 
 
-"""|]
+                      """|]
+                 in actual `shouldBe` expected
             it "has newlines and one symbol at the end" $
-              value pretty (Full.String "\n\na") `shouldBe` [r|"""
+                let actual = value pretty $ Full.String "\n\na"
+                    expected = [gql|
+                      """
 
 
-  a
-"""|]
+                        a
+                      """
+                    |]
+                 in actual `shouldBe` expected
             it "has newlines and one symbol in the middle" $
-              value pretty (Full.String "\na\n") `shouldBe` [r|"""
+                let actual = value pretty $ Full.String "\na\n"
+                    expected = [gql|
+                      """
 
-  a
+                        a
 
-"""|]
-            it "skip trailing whitespaces" $ value pretty (Full.String "  Short\ntext    ")
-              `shouldBe` [r|"""
-  Short
-  text
-"""|]
+                      """
+                    |]
+                 in actual `shouldBe` expected
+            it "skip trailing whitespaces" $
+                let actual = value pretty $ Full.String "  Short\ntext    "
+                    expected = [gql|
+                      """
+                        Short
+                        text
+                      """
+                    |]
+                 in actual `shouldBe` expected
 
     describe "definition" $
         it "indents block strings in arguments" $
@@ -128,10 +163,13 @@ spec = do
                 fieldSelection = pure $ Full.FieldSelection field
                 operation = Full.DefinitionOperation
                     $ Full.SelectionSet fieldSelection location
-             in definition pretty operation `shouldBe` [r|{
-  field(message: """
-    line1
-    line2
-  """)
-}
-|]
+                expected = Text.Lazy.snoc [gql|
+                  {
+                    field(message: """
+                      line1
+                      line2
+                    """)
+                  }
+                |] '\n'
+                actual = definition pretty operation
+             in actual `shouldBe` expected

tests/Language/GraphQL/AST/LexerSpec.hs

@@ -7,10 +7,10 @@ module Language.GraphQL.AST.LexerSpec
 import Data.Text (Text)
 import Data.Void (Void)
 import Language.GraphQL.AST.Lexer
+import Language.GraphQL.TH
 import Test.Hspec (Spec, context, describe, it)
 import Test.Hspec.Megaparsec (shouldParse, shouldFailOn, shouldSucceedOn)
 import Text.Megaparsec (ParseErrorBundle, parse)
-import Text.RawString.QQ (r)
 
 spec :: Spec
 spec = describe "Lexer" $ do
@@ -19,32 +19,32 @@ spec = describe "Lexer" $ do
             parse unicodeBOM "" `shouldSucceedOn` "\xfeff"
 
         it "lexes strings" $ do
-            parse string "" [r|"simple"|] `shouldParse` "simple"
-            parse string "" [r|" white space "|] `shouldParse` " white space "
-            parse string "" [r|"quote \""|] `shouldParse` [r|quote "|]
-            parse string "" [r|"escaped \n"|] `shouldParse` "escaped \n"
-            parse string "" [r|"slashes \\ \/"|] `shouldParse` [r|slashes \ /|]
-            parse string "" [r|"unicode \u1234\u5678\u90AB\uCDEF"|]
+            parse string "" [gql|"simple"|] `shouldParse` "simple"
+            parse string "" [gql|" white space "|] `shouldParse` " white space "
+            parse string "" [gql|"quote \""|] `shouldParse` [gql|quote "|]
+            parse string "" [gql|"escaped \n"|] `shouldParse` "escaped \n"
+            parse string "" [gql|"slashes \\ \/"|] `shouldParse` [gql|slashes \ /|]
+            parse string "" [gql|"unicode \u1234\u5678\u90AB\uCDEF"|]
                 `shouldParse` "unicode ሴ噸邫췯"
 
         it "lexes block string" $ do
-            parse blockString "" [r|"""simple"""|] `shouldParse` "simple"
-            parse blockString "" [r|""" white space """|]
+            parse blockString "" [gql|"""simple"""|] `shouldParse` "simple"
+            parse blockString "" [gql|""" white space """|]
                 `shouldParse` " white space "
-            parse blockString "" [r|"""contains " quote"""|]
-                `shouldParse` [r|contains " quote|]
-            parse blockString "" [r|"""contains \""" triplequote"""|]
-                `shouldParse` [r|contains """ triplequote|]
+            parse blockString "" [gql|"""contains " quote"""|]
+                `shouldParse` [gql|contains " quote|]
+            parse blockString "" [gql|"""contains \""" triplequote"""|]
+                `shouldParse` [gql|contains """ triplequote|]
             parse blockString "" "\"\"\"multi\nline\"\"\"" `shouldParse` "multi\nline"
             parse blockString "" "\"\"\"multi\rline\r\nnormalized\"\"\""
                 `shouldParse` "multi\nline\nnormalized"
             parse blockString "" "\"\"\"multi\rline\r\nnormalized\"\"\""
                 `shouldParse` "multi\nline\nnormalized"
-            parse blockString "" [r|"""unescaped \n\r\b\t\f\u1234"""|]
-                `shouldParse` [r|unescaped \n\r\b\t\f\u1234|]
-            parse blockString "" [r|"""slashes \\ \/"""|]
-                `shouldParse` [r|slashes \\ \/|]
-            parse blockString "" [r|"""
+            parse blockString "" [gql|"""unescaped \n\r\b\t\f\u1234"""|]
+                `shouldParse` [gql|unescaped \n\r\b\t\f\u1234|]
+            parse blockString "" [gql|"""slashes \\ \/"""|]
+                `shouldParse` [gql|slashes \\ \/|]
+            parse blockString "" [gql|"""
 
                 spans
                   multiple
@@ -84,7 +84,7 @@ spec = describe "Lexer" $ do
 
     context "Implementation tests" $ do
         it "lexes empty block strings" $
-            parse blockString "" [r|""""""|] `shouldParse` ""
+            parse blockString "" [gql|""""""|] `shouldParse` ""
         it "lexes ampersand" $
             parse amp "" "&" `shouldParse` "&"
         it "lexes schema extensions" $

tests/Language/GraphQL/AST/ParserSpec.hs

@@ -8,10 +8,10 @@ import Data.List.NonEmpty (NonEmpty(..))
 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.Megaparsec (shouldParse, shouldFailOn, shouldSucceedOn)
 import Text.Megaparsec (parse)
-import Text.RawString.QQ (r)
 
 spec :: Spec
 spec = describe "Parser" $ do
@@ -19,74 +19,74 @@ spec = describe "Parser" $ do
         parse document "" `shouldSucceedOn` "\xfeff{foo}"
 
     it "accepts block strings as argument" $
-        parse document "" `shouldSucceedOn` [r|{
+        parse document "" `shouldSucceedOn` [gql|{
               hello(text: """Argument""")
             }|]
 
     it "accepts strings as argument" $
-        parse document "" `shouldSucceedOn` [r|{
+        parse document "" `shouldSucceedOn` [gql|{
               hello(text: "Argument")
             }|]
 
     it "accepts two required arguments" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             mutation auth($username: String!, $password: String!){
               test
             }|]
 
     it "accepts two string arguments" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             mutation auth{
               test(username: "username", password: "password")
             }|]
 
     it "accepts two block string arguments" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             mutation auth{
               test(username: """username""", password: """password""")
             }|]
 
     it "parses minimal schema definition" $
-        parse document "" `shouldSucceedOn` [r|schema { query: Query }|]
+        parse document "" `shouldSucceedOn` [gql|schema { query: Query }|]
 
     it "parses minimal scalar definition" $
-        parse document "" `shouldSucceedOn` [r|scalar Time|]
+        parse document "" `shouldSucceedOn` [gql|scalar Time|]
 
     it "parses ImplementsInterfaces" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             type Person implements NamedEntity & ValuedEntity {
               name: String
             }
         |]
 
     it "parses a  type without ImplementsInterfaces" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             type Person {
               name: String
             }
         |]
 
     it "parses ArgumentsDefinition in an ObjectDefinition" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             type Person {
               name(first: String, last: String): String
             }
         |]
 
     it "parses minimal union type definition" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             union SearchResult = Photo | Person
         |]
 
     it "parses minimal interface type definition" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             interface NamedEntity {
               name: String
             }
         |]
 
     it "parses minimal enum type definition" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             enum Direction {
               NORTH
               EAST
@@ -96,7 +96,7 @@ spec = describe "Parser" $ do
         |]
 
     it "parses minimal enum type definition" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             enum Direction {
               NORTH
               EAST
@@ -106,7 +106,7 @@ spec = describe "Parser" $ do
         |]
 
     it "parses minimal input object type definition" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             input Point2D {
               x: Float
               y: Float
@@ -114,7 +114,7 @@ spec = describe "Parser" $ do
         |]
 
     it "parses minimal input enum definition with an optional pipe" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             directive @example on
               | FIELD
               | FRAGMENT_SPREAD
@@ -131,15 +131,15 @@ spec = describe "Parser" $ do
             example1 =
                 directive "example1"
                     (DirLoc.TypeSystemDirectiveLocation DirLoc.FieldDefinition)
-                    (Location {line = 2, column = 17})
+                    (Location {line = 1, column = 1})
             example2 =
                 directive "example2"
                     (DirLoc.ExecutableDirectiveLocation DirLoc.Field)
-                    (Location {line = 3, column = 17})
+                    (Location {line = 2, column = 1})
             testSchemaExtension = example1 :| [ example2 ]
-            query = [r|
-                directive @example1 on FIELD_DEFINITION
-                directive @example2 on FIELD
+            query = [gql|
+              directive @example1 on FIELD_DEFINITION
+              directive @example2 on FIELD
             |]
          in parse document "" query `shouldParse` testSchemaExtension
 
@@ -167,16 +167,16 @@ spec = describe "Parser" $ do
                           $ Node (ConstList [])
                           $ Location {line = 1, column = 33})]
                     (Location {line = 1, column = 1})
-            query = [r|directive @test(foo: [String] = []) on FIELD_DEFINITION|]
+            query = [gql|directive @test(foo: [String] = []) on FIELD_DEFINITION|]
          in parse document "" query `shouldParse` (defn :| [ ])
 
     it "parses schema extension with a new directive" $
-        parse document "" `shouldSucceedOn`[r|
+        parse document "" `shouldSucceedOn`[gql|
             extend schema @newDirective
         |]
 
     it "parses schema extension with an operation type definition" $
-        parse document "" `shouldSucceedOn` [r|extend schema { query: Query }|]
+        parse document "" `shouldSucceedOn` [gql|extend schema { query: Query }|]
 
     it "parses schema extension with an operation type and directive" $
         let newDirective = Directive "newDirective" [] $ Location 1 15
@@ -185,25 +185,25 @@ spec = describe "Parser" $ do
                 $ OperationTypeDefinition Query "Query" :| []
             testSchemaExtension = TypeSystemExtension schemaExtension
                 $ Location 1 1
-            query = [r|extend schema @newDirective { query: Query }|]
+            query = [gql|extend schema @newDirective { query: Query }|]
          in parse document "" query `shouldParse` (testSchemaExtension :| [])
 
     it "parses an object extension" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             extend type Story {
               isHiddenLocally: Boolean
             }
         |]
 
     it "rejects variables in DefaultValue" $
-        parse document "" `shouldFailOn` [r|
+        parse document "" `shouldFailOn` [gql|
             query ($book: String = "Zarathustra", $author: String = $book) {
               title
             }
         |]
 
     it "parses documents beginning with a comment" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             """
             Query
             """
@@ -213,7 +213,7 @@ spec = describe "Parser" $ do
         |]
 
     it "parses subscriptions" $
-        parse document "" `shouldSucceedOn` [r|
+        parse document "" `shouldSucceedOn` [gql|
             subscription NewMessages {
               newMessage(roomId: 123) {
                 sender

tests/Language/GraphQL/ExecuteSpec.hs

@@ -21,6 +21,7 @@ import Language.GraphQL.AST (Document, Location(..), Name)
 import Language.GraphQL.AST.Parser (document)
 import Language.GraphQL.Error
 import Language.GraphQL.Execute (execute)
+import Language.GraphQL.TH
 import qualified Language.GraphQL.Type.Schema as Schema
 import Language.GraphQL.Type
 import qualified Language.GraphQL.Type.In as In
@@ -28,7 +29,6 @@ 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.RawString.QQ (r)
 
 data PhilosopherException = PhilosopherException
     deriving Show
@@ -54,18 +54,23 @@ queryType = Out.ObjectType "Query" Nothing []
     $ HashMap.fromList
     [ ("philosopher", ValueResolver philosopherField philosopherResolver)
     , ("genres", ValueResolver genresField genresResolver)
+    , ("count", ValueResolver countField countResolver)
     ]
   where
     philosopherField =
-        Out.Field Nothing (Out.NonNullObjectType philosopherType)
+        Out.Field Nothing (Out.NamedObjectType philosopherType)
         $ HashMap.singleton "id"
         $ In.Argument Nothing (In.NamedScalarType id) Nothing
     philosopherResolver = pure $ Object mempty
     genresField =
-      let fieldType = Out.ListType $ Out.NonNullScalarType string
-       in Out.Field Nothing fieldType HashMap.empty
+        let fieldType = Out.ListType $ Out.NonNullScalarType string
+         in Out.Field Nothing fieldType HashMap.empty
     genresResolver :: Resolve (Either SomeException)
     genresResolver = throwM PhilosopherException
+    countField =
+        let fieldType = Out.NonNullScalarType int
+         in Out.Field Nothing fieldType HashMap.empty
+    countResolver = pure ""
 
 musicType :: Out.ObjectType (Either SomeException)
 musicType = Out.ObjectType "Music" Nothing []
@@ -101,6 +106,7 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
         , ("interest", ValueResolver interestField interestResolver)
         , ("majorWork", ValueResolver majorWorkField majorWorkResolver)
         , ("century", ValueResolver centuryField centuryResolver)
+        , ("firstLanguage", ValueResolver firstLanguageField firstLanguageResolver)
         ]
     firstNameField =
         Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
@@ -126,6 +132,9 @@ philosopherType = Out.ObjectType "Philosopher" Nothing []
     centuryField =
         Out.Field Nothing (Out.NonNullScalarType int) HashMap.empty
     centuryResolver = pure $ Float 18.5
+    firstLanguageField
+        = Out.Field Nothing (Out.NonNullScalarType string) HashMap.empty
+    firstLanguageResolver = pure Null
 
 workType :: Out.InterfaceType (Either SomeException)
 workType = Out.InterfaceType "Work" Nothing []
@@ -191,7 +200,7 @@ spec :: Spec
 spec =
     describe "execute" $ do
         it "rejects recursive fragments" $
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 ...cyclicFragment
               }
@@ -230,14 +239,13 @@ spec =
 
             it "errors on invalid output enum values" $
                 let data'' = Aeson.object
-                        [ "philosopher" .= Aeson.object
-                            [ "school" .= Aeson.Null
-                            ]
+                        [ "philosopher" .= Aeson.Null
                         ]
                     executionErrors = pure $ Error
-                        { message = "Enum value completion failed."
+                        { message =
+                            "Value completion error. Expected type !School, found: EXISTENTIALISM."
                         , locations = [Location 1 17]
-                        , path = []
+                        , path = [Segment "philosopher", Segment "school"]
                         }
                     expected = Response data'' executionErrors
                     Right (Right actual) = either (pure . parseError) execute'
@@ -246,14 +254,13 @@ spec =
 
             it "gives location information for non-null unions" $
                 let data'' = Aeson.object
-                        [ "philosopher" .= Aeson.object
-                            [ "interest" .= Aeson.Null
-                            ]
+                        [ "philosopher" .= Aeson.Null
                         ]
                     executionErrors = pure $ Error
-                        { message = "Union value completion failed."
+                        { message =
+                            "Value completion error. Expected type !Interest, found: { instrument: \"piano\" }."
                         , locations = [Location 1 17]
-                        , path = []
+                        , path = [Segment "philosopher", Segment "interest"]
                         }
                     expected = Response data'' executionErrors
                     Right (Right actual) = either (pure . parseError) execute'
@@ -262,14 +269,14 @@ spec =
 
             it "gives location information for invalid interfaces" $
                 let data'' = Aeson.object
-                        [ "philosopher" .= Aeson.object
-                            [ "majorWork" .= Aeson.Null
-                            ]
+                        [ "philosopher" .= Aeson.Null
                         ]
                     executionErrors = pure $ Error
-                        { message = "Interface value completion failed."
+                        { message
+                            = "Value completion error. Expected type !Work, found:\
+                            \ { title: \"Also sprach Zarathustra: Ein Buch f\252r Alle und Keinen\" }."
                         , locations = [Location 1 17]
-                        , path = []
+                        , path = [Segment "philosopher", Segment "majorWork"]
                         }
                     expected = Response data'' executionErrors
                     Right (Right actual) = either (pure . parseError) execute'
@@ -281,9 +288,10 @@ spec =
                         [ "philosopher" .= Aeson.Null
                         ]
                     executionErrors = pure $ Error
-                        { message = "Argument coercing failed."
+                        { message =
+                            "Argument \"id\" has invalid type. Expected type ID, found: True."
                         , locations = [Location 1 15]
-                        , path = []
+                        , path = [Segment "philosopher"]
                         }
                     expected = Response data'' executionErrors
                     Right (Right actual) = either (pure . parseError) execute'
@@ -292,14 +300,12 @@ spec =
 
             it "gives location information for failed result coercion" $
                 let data'' = Aeson.object
-                        [ "philosopher" .= Aeson.object
-                            [ "century" .= Aeson.Null
-                            ]
+                        [ "philosopher" .= Aeson.Null
                         ]
                     executionErrors = pure $ Error
-                        { message = "Result coercion failed."
+                        { message = "Unable to coerce result to !Int."
                         , locations = [Location 1 26]
-                        , path = []
+                        , path = [Segment "philosopher", Segment "century"]
                         }
                     expected = Response data'' executionErrors
                     Right (Right actual) = either (pure . parseError) execute'
@@ -313,13 +319,38 @@ spec =
                     executionErrors = pure $ Error
                         { message = "PhilosopherException"
                         , locations = [Location 1 3]
-                        , path = []
+                        , path = [Segment "genres"]
                         }
                     expected = Response data'' executionErrors
                     Right (Right actual) = either (pure . parseError) execute'
                         $ parse document "" "{ genres }"
                 in actual `shouldBe` expected
 
+            it "sets data to null if a root field isn't nullable" $
+                let executionErrors = pure $ Error
+                        { message = "Unable to coerce result to !Int."
+                        , locations = [Location 1 3]
+                        , path = [Segment "count"]
+                        }
+                    expected = Response Aeson.Null executionErrors
+                    Right (Right actual) = either (pure . parseError) execute'
+                        $ parse document "" "{ count }"
+                in actual `shouldBe` expected
+
+            it "detects nullability errors" $
+                let data'' = Aeson.object
+                        [ "philosopher" .= Aeson.Null
+                        ]
+                    executionErrors = pure $ Error
+                        { message = "Value completion error. Expected type !String, found: null."
+                        , locations = [Location 1 26]
+                        , path = [Segment "philosopher", Segment "firstLanguage"]
+                        }
+                    expected = Response data'' executionErrors
+                    Right (Right actual) = either (pure . parseError) execute'
+                        $ parse document "" "{ philosopher(id: \"1\") { firstLanguage } }"
+                in actual `shouldBe` expected
+
         context "Subscription" $
             it "subscribes" $
                 let data'' = Aeson.object

tests/Language/GraphQL/Validate/RulesSpec.hs

@@ -13,13 +13,13 @@ import Data.Foldable (toList)
 import qualified Data.HashMap.Strict as HashMap
 import Data.Text (Text)
 import qualified Language.GraphQL.AST as AST
+import Language.GraphQL.TH
 import Language.GraphQL.Type
 import qualified Language.GraphQL.Type.In as In
 import qualified Language.GraphQL.Type.Out as Out
 import Language.GraphQL.Validate
 import Test.Hspec (Spec, context, describe, it, shouldBe, shouldContain)
 import Text.Megaparsec (parse, errorBundlePretty)
-import Text.RawString.QQ (r)
 
 petSchema :: Schema IO
 petSchema = schema queryType Nothing (Just subscriptionType) mempty
@@ -163,7 +163,7 @@ spec =
     describe "document" $ do
         context "executableDefinitionsRule" $
             it "rejects type definitions" $
-                let queryString = [r|
+                let queryString = [gql|
                   query getDogName {
                     dog {
                       name
@@ -179,13 +179,13 @@ spec =
                         { message =
                             "Definition must be OperationDefinition or \
                             \FragmentDefinition."
-                        , locations = [AST.Location 9 19]
+                        , locations = [AST.Location 8 1]
                         }
                  in validate queryString `shouldContain` [expected]
 
         context "singleFieldSubscriptionsRule" $ do
             it "rejects multiple subscription root fields" $
-                let queryString = [r|
+                let queryString = [gql|
                   subscription sub {
                     newMessage {
                       body
@@ -198,12 +198,12 @@ spec =
                         { message =
                             "Subscription \"sub\" must select only one top \
                             \level field."
-                        , locations = [AST.Location 2 19]
+                        , locations = [AST.Location 1 1]
                         }
                  in validate queryString `shouldContain` [expected]
 
             it "rejects multiple subscription root fields coming from a fragment" $
-                let queryString = [r|
+                let queryString = [gql|
                   subscription sub {
                     ...multipleSubscriptions
                   }
@@ -220,12 +220,12 @@ spec =
                         { message =
                             "Subscription \"sub\" must select only one top \
                             \level field."
-                        , locations = [AST.Location 2 19]
+                        , locations = [AST.Location 1 1]
                         }
                  in validate queryString `shouldContain` [expected]
 
             it "finds corresponding subscription fragment" $
-                let queryString = [r|
+                let queryString = [gql|
                   subscription sub {
                     ...anotherSubscription
                     ...multipleSubscriptions
@@ -249,13 +249,13 @@ spec =
                         { message =
                             "Subscription \"sub\" must select only one top \
                             \level field."
-                        , locations = [AST.Location 2 19]
+                        , locations = [AST.Location 1 1]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "loneAnonymousOperationRule" $
             it "rejects multiple anonymous operations" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       name
@@ -274,13 +274,13 @@ spec =
                         { message =
                             "This anonymous operation must be the only defined \
                             \operation."
-                        , locations = [AST.Location 2 19]
+                        , locations = [AST.Location 1 1]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "uniqueOperationNamesRule" $
             it "rejects operations with the same name" $
-                let queryString = [r|
+                let queryString = [gql|
                   query dogOperation {
                     dog {
                       name
@@ -297,13 +297,13 @@ spec =
                         { message =
                             "There can be only one operation named \
                             \\"dogOperation\"."
-                        , locations = [AST.Location 2 19, AST.Location 8 19]
+                        , locations = [AST.Location 1 1, AST.Location 7 1]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "uniqueFragmentNamesRule" $
             it "rejects fragments with the same name" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ...fragmentOne
@@ -324,13 +324,13 @@ spec =
                         { message =
                             "There can be only one fragment named \
                             \\"fragmentOne\"."
-                        , locations = [AST.Location 8 19, AST.Location 12 19]
+                        , locations = [AST.Location 7 1, AST.Location 11 1]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "fragmentSpreadTargetDefinedRule" $
             it "rejects the fragment spread without a target" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ...undefinedFragment
@@ -341,13 +341,13 @@ spec =
                         { message =
                             "Fragment target \"undefinedFragment\" is \
                             \undefined."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "fragmentSpreadTypeExistenceRule" $ do
             it "rejects fragment spreads without an unknown target type" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ...notOnExistingType
@@ -362,12 +362,12 @@ spec =
                             "Fragment \"notOnExistingType\" is specified on \
                             \type \"NotInSchema\" which doesn't exist in the \
                             \schema."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "rejects inline fragments without a target" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     ... on NotInSchema {
                       name
@@ -378,13 +378,13 @@ spec =
                         { message =
                             "Inline fragment is specified on type \
                             \\"NotInSchema\" which doesn't exist in the schema."
-                        , locations = [AST.Location 3 21]
+                        , locations = [AST.Location 2 3]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "fragmentsOnCompositeTypesRule" $ do
             it "rejects fragments on scalar types" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ...fragOnScalar
@@ -398,12 +398,12 @@ spec =
                         { message =
                             "Fragment cannot condition on non composite type \
                             \\"Int\"."
-                        , locations = [AST.Location 7 19]
+                        , locations = [AST.Location 6 1]
                         }
                  in validate queryString `shouldContain` [expected]
 
             it "rejects inline fragments on scalar types" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     ... on Boolean {
                       name
@@ -414,13 +414,13 @@ spec =
                         { message =
                             "Fragment cannot condition on non composite type \
                             \\"Boolean\"."
-                        , locations = [AST.Location 3 21]
+                        , locations = [AST.Location 2 3]
                         }
                 in validate queryString `shouldContain` [expected]
 
         context "noUnusedFragmentsRule" $
             it "rejects unused fragments" $
-                let queryString = [r|
+                let queryString = [gql|
                   fragment nameFragment on Dog { # unused
                     name
                   }
@@ -434,13 +434,13 @@ spec =
                     expected = Error
                         { message =
                             "Fragment \"nameFragment\" is never used."
-                        , locations = [AST.Location 2 19]
+                        , locations = [AST.Location 1 1]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "noFragmentCyclesRule" $
             it "rejects spreads that form cycles" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ...nameFragment
@@ -460,20 +460,20 @@ spec =
                             "Cannot spread fragment \"barkVolumeFragment\" \
                             \within itself (via barkVolumeFragment -> \
                             \nameFragment -> barkVolumeFragment)."
-                        , locations = [AST.Location 11 19]
+                        , locations = [AST.Location 10 1]
                         }
                     error2 = Error
                         { message =
                             "Cannot spread fragment \"nameFragment\" within \
                             \itself (via nameFragment -> barkVolumeFragment -> \
                             \nameFragment)."
-                        , locations = [AST.Location 7 19]
+                        , locations = [AST.Location 6 1]
                         }
                  in validate queryString `shouldBe` [error1, error2]
 
         context "uniqueArgumentNamesRule" $
             it "rejects duplicate field arguments" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       isHousetrained(atOtherHomes: true, atOtherHomes: true)
@@ -484,13 +484,13 @@ spec =
                         { message =
                             "There can be only one argument named \
                             \\"atOtherHomes\"."
-                        , locations = [AST.Location 4 38, AST.Location 4 58]
+                        , locations = [AST.Location 3 20, AST.Location 3 40]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "uniqueDirectiveNamesRule" $
             it "rejects more than one directive per location" $
-                let queryString = [r|
+                let queryString = [gql|
                   query ($foo: Boolean = true, $bar: Boolean = false) {
                     dog @skip(if: $foo) @skip(if: $bar) {
                       name
@@ -500,13 +500,13 @@ spec =
                     expected = Error
                         { message =
                             "There can be only one directive named \"skip\"."
-                        , locations = [AST.Location 3 25, AST.Location 3 41]
+                        , locations = [AST.Location 2 7, AST.Location 2 23]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "uniqueVariableNamesRule" $
             it "rejects duplicate variables" $
-                let queryString = [r|
+                let queryString = [gql|
                   query houseTrainedQuery($atOtherHomes: Boolean, $atOtherHomes: Boolean) {
                     dog {
                       isHousetrained(atOtherHomes: $atOtherHomes)
@@ -517,13 +517,13 @@ spec =
                         { message =
                             "There can be only one variable named \
                             \\"atOtherHomes\"."
-                        , locations = [AST.Location 2 43, AST.Location 2 67]
+                        , locations = [AST.Location 1 25, AST.Location 1 49]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "variablesAreInputTypesRule" $
             it "rejects non-input types as variables" $
-                let queryString = [r|
+                let queryString = [gql|
                   query takesDogBang($dog: Dog!) {
                     dog {
                       isHousetrained(atOtherHomes: $dog)
@@ -534,13 +534,13 @@ spec =
                         { message =
                             "Variable \"$dog\" cannot be non-input type \
                             \\"Dog\"."
-                        , locations = [AST.Location 2 38]
+                        , locations = [AST.Location 1 20]
                         }
                  in validate queryString `shouldContain` [expected]
 
         context "noUndefinedVariablesRule" $
             it "rejects undefined variables" $
-                let queryString = [r|
+                let queryString = [gql|
                   query variableIsNotDefinedUsedInSingleFragment {
                     dog {
                       ...isHousetrainedFragment
@@ -556,13 +556,13 @@ spec =
                             "Variable \"$atOtherHomes\" is not defined by \
                             \operation \
                             \\"variableIsNotDefinedUsedInSingleFragment\"."
-                        , locations = [AST.Location 9 50]
+                        , locations = [AST.Location 8 32]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "noUnusedVariablesRule" $
             it "rejects unused variables" $
-                let queryString = [r|
+                let queryString = [gql|
                   query variableUnused($atOtherHomes: Boolean) {
                     dog {
                       isHousetrained
@@ -573,13 +573,13 @@ spec =
                         { message =
                             "Variable \"$atOtherHomes\" is never used in \
                             \operation \"variableUnused\"."
-                        , locations = [AST.Location 2 40]
+                        , locations = [AST.Location 1 22]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "uniqueInputFieldNamesRule" $
             it "rejects duplicate fields in input objects" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     findDog(complex: { name: "Fido", name: "Jack" }) {
                       name
@@ -589,13 +589,13 @@ spec =
                     expected = Error
                         { message =
                             "There can be only one input field named \"name\"."
-                        , locations = [AST.Location 3 40, AST.Location 3 54]
+                        , locations = [AST.Location 2 22, AST.Location 2 36]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "fieldsOnCorrectTypeRule" $
             it "rejects undefined fields" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       meowVolume
@@ -605,13 +605,13 @@ spec =
                     expected = Error
                         { message =
                             "Cannot query field \"meowVolume\" on type \"Dog\"."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "scalarLeafsRule" $
             it "rejects scalar fields with not empty selection set" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       barkVolume {
@@ -624,13 +624,13 @@ spec =
                         { message =
                             "Field \"barkVolume\" must not have a selection \
                             \since type \"Int\" has no subfields."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "knownArgumentNamesRule" $ do
             it "rejects field arguments missing in the type" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       doesKnowCommand(command: CLEAN_UP_HOUSE, dogCommand: SIT)
@@ -641,12 +641,12 @@ spec =
                         { message =
                             "Unknown argument \"command\" on field \
                             \\"Dog.doesKnowCommand\"."
-                        , locations = [AST.Location 4 39]
+                        , locations = [AST.Location 3 21]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "rejects directive arguments missing in the definition" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       isHousetrained(atOtherHomes: true) @include(unless: false, if: true)
@@ -657,13 +657,13 @@ spec =
                         { message =
                             "Unknown argument \"unless\" on directive \
                             \\"@include\"."
-                        , locations = [AST.Location 4 67]
+                        , locations = [AST.Location 3 49]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "knownDirectiveNamesRule" $
             it "rejects undefined directives" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       isHousetrained(atOtherHomes: true) @ignore(if: true)
@@ -672,13 +672,13 @@ spec =
                 |]
                     expected = Error
                         { message = "Unknown directive \"@ignore\"."
-                        , locations = [AST.Location 4 58]
+                        , locations = [AST.Location 3 40]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "knownInputFieldNamesRule" $
             it "rejects undefined input object fields" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     findDog(complex: { favoriteCookieFlavor: "Bacon", name: "Jack" }) {
                       name
@@ -689,13 +689,13 @@ spec =
                         { message =
                             "Field \"favoriteCookieFlavor\" is not defined \
                             \by type \"DogData\"."
-                        , locations = [AST.Location 3 40]
+                        , locations = [AST.Location 2 22]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "directivesInValidLocationsRule" $
             it "rejects directives in invalid locations" $
-                let queryString = [r|
+                let queryString = [gql|
                   query @skip(if: $foo) {
                     dog {
                       name
@@ -705,13 +705,13 @@ spec =
                     expected = Error
                         { message =
                             "Directive \"@skip\" may not be used on QUERY."
-                        , locations = [AST.Location 2 25]
+                        , locations = [AST.Location 1 7]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "overlappingFieldsCanBeMergedRule" $ do
             it "fails to merge fields of mismatching types" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       name: nickname
@@ -725,12 +725,12 @@ spec =
                             \\"name\" are different fields. Use different \
                             \aliases on the fields to fetch both if this was \
                             \intentional."
-                        , locations = [AST.Location 4 23, AST.Location 5 23]
+                        , locations = [AST.Location 3 5, AST.Location 4 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "fails if the arguments of the same field don't match" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       doesKnowCommand(dogCommand: SIT)
@@ -744,12 +744,12 @@ spec =
                             \have different arguments. Use different aliases \
                             \on the fields to fetch both if this was \
                             \intentional."
-                        , locations = [AST.Location 4 23, AST.Location 5 23]
+                        , locations = [AST.Location 3 5, AST.Location 4 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "fails to merge same-named field and alias" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       doesKnowCommand(dogCommand: SIT)
@@ -763,12 +763,12 @@ spec =
                             \\"doesKnowCommand\" and \"isHousetrained\" are \
                             \different fields. Use different aliases on the \
                             \fields to fetch both if this was intentional."
-                        , locations = [AST.Location 4 23, AST.Location 5 23]
+                        , locations = [AST.Location 3 5, AST.Location 4 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "looks for fields after a successfully merged field pair" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       name
@@ -786,13 +786,13 @@ spec =
                             \\"doesKnowCommand\" and \"isHousetrained\" are \
                             \different fields. Use different aliases on the \
                             \fields to fetch both if this was intentional."
-                        , locations = [AST.Location 5 23, AST.Location 9 23]
+                        , locations = [AST.Location 4 5, AST.Location 8 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "possibleFragmentSpreadsRule" $ do
             it "rejects object inline spreads outside object scope" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ... on Cat {
@@ -805,12 +805,12 @@ spec =
                         { message =
                             "Fragment cannot be spread here as objects of type \
                             \\"Dog\" can never be of type \"Cat\"."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "rejects object named spreads outside object scope" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       ... catInDogFragmentInvalid
@@ -826,13 +826,13 @@ spec =
                             "Fragment \"catInDogFragmentInvalid\" cannot be \
                             \spread here as objects of type \"Dog\" can never \
                             \be of type \"Cat\"."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "providedRequiredInputFieldsRule" $
             it "rejects missing required input fields" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     findDog(complex: { name: null }) {
                       name
@@ -843,13 +843,13 @@ spec =
                         { message =
                             "Input field \"name\" of type \"DogData\" is \
                             \required, but it was not provided."
-                        , locations = [AST.Location 3 38]
+                        , locations = [AST.Location 2 20]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "providedRequiredArgumentsRule" $ do
             it "checks for (non-)nullable arguments" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       doesKnowCommand(dogCommand: null)
@@ -861,13 +861,13 @@ spec =
                             "Field \"doesKnowCommand\" argument \"dogCommand\" \
                             \of type \"DogCommand\" is required, but it was \
                             \not provided."
-                        , locations = [AST.Location 4 23]
+                        , locations = [AST.Location 3 5]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "variablesInAllowedPositionRule" $ do
             it "rejects wrongly typed variable arguments" $
-                let queryString = [r|
+                let queryString = [gql|
                   query dogCommandArgQuery($dogCommandArg: DogCommand) {
                     dog {
                       doesKnowCommand(dogCommand: $dogCommandArg)
@@ -879,12 +879,12 @@ spec =
                             "Variable \"$dogCommandArg\" of type \
                             \\"DogCommand\" used in position expecting type \
                             \\"!DogCommand\"."
-                        , locations = [AST.Location 2 44]
+                        , locations = [AST.Location 1 26]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "rejects wrongly typed variable arguments" $
-                let queryString = [r|
+                let queryString = [gql|
                   query intCannotGoIntoBoolean($intArg: Int) {
                     dog {
                       isHousetrained(atOtherHomes: $intArg)
@@ -895,13 +895,13 @@ spec =
                         { message =
                             "Variable \"$intArg\" of type \"Int\" used in \
                             \position expecting type \"Boolean\"."
-                        , locations = [AST.Location 2 48]
+                        , locations = [AST.Location 1 30]
                         }
                  in validate queryString `shouldBe` [expected]
 
         context "valuesOfCorrectTypeRule" $ do
             it "rejects values of incorrect types" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     dog {
                       isHousetrained(atOtherHomes: 3)
@@ -911,12 +911,12 @@ spec =
                     expected = Error
                         { message =
                             "Value 3 cannot be coerced to type \"Boolean\"."
-                        , locations = [AST.Location 4 52]
+                        , locations = [AST.Location 3 34]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "uses the location of a single list value" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     cat {
                       doesKnowCommands(catCommands: [3])
@@ -926,12 +926,12 @@ spec =
                     expected = Error
                         { message =
                             "Value 3 cannot be coerced to type \"!CatCommand\"."
-                        , locations = [AST.Location 4 54]
+                        , locations = [AST.Location 3 36]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "validates input object properties once" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     findDog(complex: { name: 3 }) {
                       name
@@ -941,12 +941,12 @@ spec =
                     expected = Error
                         { message =
                             "Value 3 cannot be coerced to type \"!String\"."
-                        , locations = [AST.Location 3 46]
+                        , locations = [AST.Location 2 28]
                         }
                  in validate queryString `shouldBe` [expected]
 
             it "checks for required list members" $
-                let queryString = [r|
+                let queryString = [gql|
                   {
                     cat {
                       doesKnowCommands(catCommands: [null])
@@ -957,6 +957,6 @@ spec =
                         { message =
                             "List of non-null values of type \"CatCommand\" \
                             \cannot contain null values."
-                        , locations = [AST.Location 4 54]
+                        , locations = [AST.Location 3 36]
                         }
                  in validate queryString `shouldBe` [expected]

tests/Test/DirectiveSpec.hs

@@ -12,11 +12,11 @@ import Data.Aeson (object, (.=))
 import qualified Data.Aeson as Aeson
 import qualified Data.HashMap.Strict as HashMap
 import Language.GraphQL
+import Language.GraphQL.TH
 import Language.GraphQL.Type
 import qualified Language.GraphQL.Type.Out as Out
 import Test.Hspec (Spec, describe, it)
 import Test.Hspec.GraphQL
-import Text.RawString.QQ (r)
 
 experimentalResolver :: Schema IO
 experimentalResolver = schema queryType Nothing Nothing mempty
@@ -33,7 +33,7 @@ spec :: Spec
 spec =
     describe "Directive executor" $ do
         it "should be able to @skip fields" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 experimentalField @skip(if: true)
               }
@@ -43,7 +43,7 @@ spec =
             actual `shouldResolveTo` emptyObject
 
         it "should not skip fields if @skip is false" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 experimentalField @skip(if: false)
               }
@@ -56,7 +56,7 @@ spec =
             actual `shouldResolveTo` expected
 
         it "should skip fields if @include is false" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 experimentalField @include(if: false)
               }
@@ -66,7 +66,7 @@ spec =
             actual `shouldResolveTo` emptyObject
 
         it "should be able to @skip a fragment spread" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 ...experimentalFragment @skip(if: true)
               }
@@ -80,7 +80,7 @@ spec =
             actual `shouldResolveTo` emptyObject
 
         it "should be able to @skip an inline fragment" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 ... on Query @skip(if: true) {
                   experimentalField

tests/Test/FragmentSpec.hs

@@ -15,9 +15,9 @@ import Data.Text (Text)
 import Language.GraphQL
 import Language.GraphQL.Type
 import qualified Language.GraphQL.Type.Out as Out
+import Language.GraphQL.TH
 import Test.Hspec (Spec, describe, it)
 import Test.Hspec.GraphQL
-import Text.RawString.QQ (r)
 
 size :: (Text, Value)
 size = ("size", String "L")
@@ -34,16 +34,18 @@ garment typeName =
     )
 
 inlineQuery :: Text
-inlineQuery = [r|{
-  garment {
-    ... on Hat {
-      circumference
-    }
-    ... on Shirt {
-      size
+inlineQuery = [gql|
+  {
+    garment {
+      ... on Hat {
+        circumference
+      }
+      ... on Shirt {
+        size
+      }
     }
   }
-}|]
+|]
 
 shirtType :: Out.ObjectType IO
 shirtType = Out.ObjectType "Shirt" Nothing [] $ HashMap.fromList
@@ -106,12 +108,14 @@ spec = do
              in actual `shouldResolveTo` expected
 
         it "embeds inline fragments without type" $ do
-            let sourceQuery = [r|{
-              circumference
-              ... {
-                size
+            let sourceQuery = [gql|
+              {
+                circumference
+                ... {
+                  size
+                }
               }
-            }|]
+            |]
             actual <- graphql (toSchema "circumference" circumference) sourceQuery
             let expected = HashMap.singleton "data"
                     $ Aeson.object
@@ -121,16 +125,18 @@ spec = do
              in actual `shouldResolveTo` expected
 
         it "evaluates fragments on Query" $ do
-            let sourceQuery = [r|{
-              ... {
-                size
+            let sourceQuery = [gql|
+              {
+                ... {
+                  size
+                }
               }
-            }|]
+            |]
              in graphql (toSchema "size" size) `shouldResolve` sourceQuery
 
     describe "Fragment spread executor" $ do
         it "evaluates fragment spreads" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 ...circumferenceFragment
               }
@@ -148,7 +154,7 @@ spec = do
              in actual `shouldResolveTo` expected
 
         it "evaluates nested fragments" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 garment {
                   ...circumferenceFragment
@@ -174,7 +180,7 @@ spec = do
              in actual `shouldResolveTo` expected
 
         it "considers type condition" $ do
-            let sourceQuery = [r|
+            let sourceQuery = [gql|
               {
                 garment {
                   ...circumferenceFragment

tests/Test/RootOperationSpec.hs

@@ -12,7 +12,7 @@ import Data.Aeson ((.=), object)
 import qualified Data.HashMap.Strict as HashMap
 import Language.GraphQL
 import Test.Hspec (Spec, describe, it)
-import Text.RawString.QQ (r)
+import Language.GraphQL.TH
 import Language.GraphQL.Type
 import qualified Language.GraphQL.Type.Out as Out
 import Test.Hspec.GraphQL
@@ -42,7 +42,7 @@ spec :: Spec
 spec =
     describe "Root operation type" $ do
         it "returns objects from the root resolvers" $ do
-            let querySource = [r|
+            let querySource = [gql|
               {
                 garment {
                   circumference
@@ -59,7 +59,7 @@ spec =
             actual `shouldResolveTo` expected
 
         it "chooses Mutation" $ do
-            let querySource = [r|
+            let querySource = [gql|
               mutation {
                 incrementCircumference
               }