Simplify Schema definition API
Now there is one `Resolver` type and the `Output` and `Scalar` types have been removed. This should be closer to the final Schema definition API.
This commit is contained in:
Danny Navarro
parent
8ee50727bd
commit
770df82718
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@ -14,10 +14,9 @@ import Data.GraphQL.Schema (Schema(..))
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import qualified Data.GraphQL.Schema as Schema
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execute
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:: Alternative m
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=> Schema m -> Schema.Subs -> Document -> m Aeson.Value
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execute (Schema resolvm) subs =
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fmap Aeson.toJSON . Schema.withFields resolvm . rootFields subs
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:: Alternative f
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=> Schema.Schema f -> Schema.Subs -> Document -> f Aeson.Value
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execute (Schema resolvs) subs = Schema.resolvers resolvs . rootFields subs
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rootFields :: Schema.Subs -> Document -> [Field]
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rootFields subs (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) =
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@ -1,111 +1,120 @@
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{-# LANGUAGE CPP #-}
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{-# LANGUAGE LambdaCase #-}
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module Data.GraphQL.Schema
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( Schema(..)
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, QueryRoot
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, ResolverO
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, ResolverM
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, Output(..)
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, Resolver
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, Subs
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, Scalar(..)
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, withField
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, withFieldFinal
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, withFields
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, withArgument
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, outputTraverse
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, object
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, objectA
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, scalar
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, scalarA
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, array
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, arrayA
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, enum
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, enumA
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, resolvers
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, fields
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-- * Reexports
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-- * AST Reexports
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, Field
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, Argument
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, Argument(..)
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, Value(..)
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, StringValue(..)
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) where
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#if !MIN_VERSION_base(4,8,0)
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import Control.Applicative (pure, (<|>))
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import Data.Foldable (foldMap)
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import Data.Traversable (traverse)
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import Data.Monoid (Monoid(mempty,mappend))
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#else
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import Data.Monoid (Alt(Alt,getAlt))
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#endif
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import Control.Applicative
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import Control.Applicative (Alternative, empty)
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import Data.Maybe (catMaybes)
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import Data.Foldable (fold)
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import Data.String (IsString(fromString))
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import Data.Aeson (ToJSON(toJSON))
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import qualified Data.Aeson as Aeson
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import Data.HashMap.Strict (HashMap)
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import qualified Data.HashMap.Strict as HashMap
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import Data.Text (Text, pack)
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import Data.Text (Text)
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import qualified Data.Text as T (null)
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import Data.GraphQL.AST
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data Schema f = Schema (QueryRoot f)
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data Schema f = Schema [Resolver f]
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type QueryRoot f = ResolverM f
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-- TODO: Come up with a unique data type or better renaming
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type ResolverM f = Field -> f (HashMap Text Output)
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type ResolverO f = [Field] -> f Output
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data Output = OutputObject (HashMap Text Output)
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| OutputList [Output]
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| OutputScalar Scalar
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| OutputEnum Text
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deriving (Show)
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type Resolver f = Field -> f Aeson.Object
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type Subs = Text -> Maybe Text
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-- TODO: GraphQL spec for Integer Scalar is 32bits
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data Scalar = ScalarInt Int
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| ScalarFloat Double
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| ScalarString Text
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| ScalarBoolean Bool
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| ScalarID Text
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deriving (Show)
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object :: Alternative f => Text -> [Resolver f] -> Resolver f
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object name resolvs = objectA name $ \case
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[] -> resolvs
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_ -> empty
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instance IsString Scalar where
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fromString = ScalarString . pack
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objectA
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:: Alternative f
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=> Text -> ([Argument] -> [Resolver f]) -> Resolver f
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objectA name f fld@(Field _ _ args _ sels) =
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withField name (resolvers (f args) $ fields sels) fld
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instance ToJSON Scalar where
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toJSON (ScalarInt x) = toJSON x
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toJSON (ScalarFloat x) = toJSON x
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toJSON (ScalarString x) = toJSON x
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toJSON (ScalarBoolean x) = toJSON x
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toJSON (ScalarID x) = toJSON x
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scalar :: (Alternative f, Aeson.ToJSON a) => Text -> a -> Resolver f
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scalar name s = scalarA name $ \case
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[] -> pure s
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_ -> empty
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instance ToJSON Output where
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toJSON (OutputObject x) = toJSON $ toJSON <$> x
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toJSON (OutputList x) = toJSON $ toJSON <$> x
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toJSON (OutputScalar x) = toJSON x
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toJSON (OutputEnum x) = toJSON x
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scalarA
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:: (Alternative f, Aeson.ToJSON a)
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=> Text -> ([Argument] -> f a) -> Resolver f
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scalarA name f fld@(Field _ _ args _ []) = withField name (f args) fld
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scalarA _ _ _ = empty
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-- * Helpers
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array :: Alternative f => Text -> [[Resolver f]] -> Resolver f
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array name resolvs = arrayA name $ \case
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[] -> resolvs
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_ -> empty
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withField :: Alternative f => Text -> ([Argument] -> ResolverO f) -> ResolverM f
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withField n f (Field alias name' args _ sels) =
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if n == name'
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then HashMap.singleton aliasOrName <$> f args (fields sels)
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else empty
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where
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aliasOrName = if T.null alias then name' else alias
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arrayA
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:: Alternative f
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=> Text -> ([Argument] -> [[Resolver f]]) -> Resolver f
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arrayA name f fld@(Field _ _ args _ sels) =
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withField name (traverse (flip resolvers $ fields sels) $ f args) fld
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withFieldFinal :: Alternative f => Text -> Output -> ResolverM f
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withFieldFinal n o fld@(Field _ _ [] _ []) = withField n (\_ _ -> pure o) fld
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withFieldFinal _ _ _ = empty
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enum :: Alternative f => Text -> f [Text] -> Resolver f
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enum name enums = enumA name $ \case
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[] -> enums
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_ -> empty
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withFields :: Alternative f => ResolverM f -> ResolverO f
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withFields f = fmap (OutputObject . fold) . traverse f
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enumA :: Alternative f => Text -> ([Argument] -> f [Text]) -> Resolver f
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enumA name f fld@(Field _ _ args _ []) = withField name (f args) fld
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enumA _ _ _ = empty
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outputTraverse :: Applicative f => (a -> f Output) -> [a] -> f Output
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outputTraverse f = fmap OutputList . traverse f
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withField
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:: (Alternative f, Aeson.ToJSON a)
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=> Text -> f a -> Field -> f (HashMap Text Aeson.Value)
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withField name f (Field alias name' _ _ _) =
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if name == name'
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then fmap (HashMap.singleton aliasOrName . Aeson.toJSON) f
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else empty
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where
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aliasOrName = if T.null alias then name' else alias
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withArgument :: Text -> [Argument] -> Maybe Scalar
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withArgument x [Argument n s] = if x == n then scalarValue s else Nothing
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withArgument _ _ = Nothing
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scalarValue :: Value -> Maybe Scalar
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scalarValue (ValueInt x) = Just . ScalarInt $ fromIntegral x
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scalarValue (ValueString (StringValue x)) = Just $ ScalarString x
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scalarValue _ = Nothing
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fields :: SelectionSet -> [Field]
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fields = catMaybes . fmap field
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resolvers :: Alternative f => [Resolver f] -> [Field] -> f Aeson.Value
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resolvers resolvs =
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fmap (Aeson.toJSON . fold)
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. traverse (\fld -> getAlt $ foldMap (Alt . ($ fld)) resolvs)
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field :: Selection -> Maybe Field
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field (SelectionField x) = Just x
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field _ = Nothing
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fields :: SelectionSet -> [Field]
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fields = catMaybes . fmap field
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#if !MIN_VERSION_base(4,8,0)
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newtype Alt f a = Alt {getAlt :: f a}
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instance Alternative f => Monoid (Alt f a) where
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mempty = Alt empty
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Alt x `mappend` Alt y = Alt $ x <|> y
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#endif
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@ -1,55 +1,45 @@
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{-# LANGUAGE CPP #-}
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{-# LANGUAGE LambdaCase #-}
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{-# LANGUAGE OverloadedStrings #-}
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module Test.StarWars.Schema where
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import Control.Applicative ((<|>), Alternative, empty)
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import Control.Applicative (Alternative, empty)
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#if !MIN_VERSION_base(4,8,0)
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import Control.Applicative ((<$>))
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import Data.Traversable (traverse)
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#endif
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import Data.GraphQL.Schema
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import qualified Data.GraphQL.Schema as Schema
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import Test.StarWars.Data
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-- * Schema
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-- See https://github.com/graphql/graphql-js/blob/master/src/__tests__/starWarsSchema.js
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schema :: (Alternative m, Monad m) => Schema m
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schema = Schema query
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schema :: Alternative f => Schema f
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schema = Schema [hero, human, droid]
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query :: (Alternative m, Monad m) => ResolverM m
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query fld =
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withField "hero" hero fld
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<|> withField "human" human fld
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<|> withField "droid" droid fld
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hero :: Alternative f => Resolver f
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hero = Schema.objectA "hero" $ \case
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[] -> character artoo
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[Argument "episode" (ValueInt n)] -> character $ getHero (fromIntegral n)
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_ -> empty
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hero :: Alternative f => [Argument] -> ResolverO f
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hero [] = characterFields artoo
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hero args =
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case withArgument "episode" args of
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Just (ScalarInt n) -> characterFields $ getHero n
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_ -> const empty
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human :: Alternative f => Resolver f
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human = Schema.objectA "human" $ \case
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[Argument "id" (ValueString (StringValue i))] -> character =<< getHuman i
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_ -> empty
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human :: (Alternative m, Monad m) => [Argument] -> ResolverO m
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human args flds =
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case withArgument "id" args of
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Just (ScalarString i) -> flip characterFields flds =<< getHuman i
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_ -> empty
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droid :: Alternative f => Resolver f
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droid = Schema.objectA "droid" $ \case
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[Argument "id" (ValueString (StringValue i))] -> character =<< getDroid i
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_ -> empty
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droid :: (Alternative m, Monad m) => [Argument] -> ResolverO m
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droid args flds =
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case withArgument "id" args of
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Just (ScalarString i) -> flip characterFields flds =<< getDroid i
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_ -> empty
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characterField :: Alternative f => Character -> ResolverM f
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characterField char fld =
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withFieldFinal "id" (OutputScalar . ScalarString . id_ $ char) fld
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<|> withFieldFinal "name" (OutputScalar . ScalarString . name $ char) fld
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<|> withField "friends" friends' fld
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<|> withField "appearsIn" appears' fld
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where
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friends' [] flds = outputTraverse (`characterFields` flds) $ getFriends char
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friends' _ _ = empty
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appears' [] [] = outputTraverse (fmap OutputEnum . getEpisode) $ appearsIn char
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appears' _ _ = empty
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characterFields :: Alternative f => Character -> ResolverO f
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characterFields = withFields . characterField
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character :: Alternative f => Character -> [Resolver f]
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character char =
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[ Schema.scalar "id" $ id_ char
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, Schema.scalar "name" $ name char
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, Schema.array "friends" $ character <$> getFriends char
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, Schema.enum "appearsIn" . traverse getEpisode $ appearsIn char
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]
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