Validate required input fields

src/Language/GraphQL/AST/Document.hs

@@ -1,5 +1,7 @@
+{-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE Safe #-}
 
 -- | This module defines an abstract syntax tree for the @GraphQL@ language. It
@@ -75,10 +77,13 @@ instance Ord Location where
 
 -- | Contains some tree node with a location.
 data Node a = Node
-    { value :: a
+    { node :: a
     , location :: Location
     } deriving (Eq, Show)
 
+instance Functor Node where
+    fmap f Node{..} = Node (f node) location
+
 -- ** Document
 
 -- | GraphQL document.
@@ -241,8 +246,11 @@ data ConstValue
 -- | Key-value pair.
 --
 -- A list of 'ObjectField's represents a GraphQL object type.
-data ObjectField a = ObjectField Name a Location
-    deriving (Eq, Show)
+data ObjectField a = ObjectField
+    { name :: Name
+    , value :: Node a
+    , location :: Location
+    } deriving (Eq, Show)
 
 -- ** Variables
 

src/Language/GraphQL/AST/Encoder.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE ExplicitForAll #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE Safe #-}
 
 -- | This module defines a minifier and a printer for the @GraphQL@ language.
@@ -101,7 +102,7 @@ variableDefinition formatter variableDefinition' =
      in variable variableName
     <> eitherFormat formatter ": " ":"
     <> type' variableType
-    <> maybe mempty (defaultValue formatter) (Full.value <$> defaultValue')
+    <> maybe mempty (defaultValue formatter) (Full.node <$> defaultValue')
 
 defaultValue :: Formatter -> Full.ConstValue -> Lazy.Text
 defaultValue formatter val
@@ -164,7 +165,7 @@ argument :: Formatter -> Full.Argument -> Lazy.Text
 argument formatter (Full.Argument name value' _)
     = Lazy.Text.fromStrict name
     <> colon formatter
-    <> value formatter (Full.value value')
+    <> value formatter (Full.node value')
 
 -- * Fragments
 
@@ -222,8 +223,8 @@ fromConstValue (Full.ConstEnum x) = Full.Enum x
 fromConstValue (Full.ConstList x) = Full.List $ fromConstValue <$> x
 fromConstValue (Full.ConstObject x) = Full.Object $ fromConstObjectField <$> x
   where
-    fromConstObjectField (Full.ObjectField key value' location) =
-        Full.ObjectField key (fromConstValue value') location
+    fromConstObjectField Full.ObjectField{value = value', ..} =
+        Full.ObjectField name (fromConstValue <$> value') location
 
 booleanValue :: Bool -> Lazy.Text
 booleanValue True  = "true"
@@ -292,7 +293,7 @@ objectValue formatter = intercalate $ objectField formatter
         . fmap f
 
 objectField :: Formatter -> Full.ObjectField Full.Value -> Lazy.Text
-objectField formatter (Full.ObjectField name value' _) =
+objectField formatter (Full.ObjectField name (Full.Node value' _) _) =
     Lazy.Text.fromStrict name <> colon formatter <> value formatter value'
 
 -- | Converts a 'Type' a type into a string.

src/Language/GraphQL/AST/Parser.hs

@@ -461,7 +461,7 @@ value = Full.Variable <$> variable
     <|> Full.String <$> stringValue
     <|> Full.Enum <$> try enumValue
     <|> Full.List <$> brackets (some value)
-    <|> Full.Object <$> braces (some $ objectField value)
+    <|> Full.Object <$> braces (some $ objectField $ valueNode value)
     <?> "Value"
 
 constValue :: Parser Full.ConstValue
@@ -472,7 +472,7 @@ constValue = Full.ConstFloat <$> try float
     <|> Full.ConstString <$> stringValue
     <|> Full.ConstEnum <$> try enumValue
     <|> Full.ConstList <$> brackets (some constValue)
-    <|> Full.ConstObject <$> braces (some $ objectField constValue)
+    <|> Full.ConstObject <$> braces (some $ objectField $ valueNode constValue)
     <?> "Value"
 
 booleanValue :: Parser Bool
@@ -493,7 +493,7 @@ stringValue = blockString <|> string <?> "StringValue"
 nullValue :: Parser Text
 nullValue = symbol "null" <?> "NullValue"
 
-objectField :: Parser a -> Parser (Full.ObjectField a)
+objectField :: forall a. Parser (Full.Node a) -> Parser (Full.ObjectField a)
 objectField valueParser = label "ObjectField" $ do
     location <- getLocation
     fieldName <- name