Add LocalTime and TimeOfDay instances

src/Language/GraphQL/Class.hs

@@ -24,13 +24,20 @@ import qualified Data.Text as Text
 import Data.Time
     ( Day
     , DiffTime
+    , LocalTime(..)
     , NominalDiffTime
+    , TimeOfDay(..)
     , UTCTime(..)
     , showGregorian
     , secondsToNominalDiffTime
     , secondsToDiffTime
     )
-import Data.Time.Format.ISO8601 (formatParseM, iso8601Format, iso8601Show)
+import Data.Time.Format.ISO8601
+    ( ISO8601(..)
+    , formatParseM
+    , iso8601Format
+    , iso8601Show
+    )
 
 fromGraphQLToIntegral :: Integral a => Type.Value -> Maybe a
 fromGraphQLToIntegral (Type.Int value) = Just $ fromIntegral value
@@ -40,6 +47,13 @@ fromGraphQLToIntegral (Type.String value) =
         _conversionError -> Nothing
 fromGraphQLToIntegral _ = Nothing
 
+iso8601ToGraphQL :: ISO8601 t => t -> Type.Value
+iso8601ToGraphQL = Type.String . Text.pack . iso8601Show
+
+fromGraphQLToISO8601 :: ISO8601 t => Type.Value -> Maybe t
+fromGraphQLToISO8601 (Type.String value') = formatParseM iso8601Format $ Text.unpack value'
+fromGraphQLToISO8601 _ = Nothing
+
 -- | Instances of this typeclass can be converted to GraphQL internal
 -- representation.
 class ToGraphQL a
@@ -133,7 +147,15 @@ instance ToGraphQL NominalDiffTime
 
 instance ToGraphQL UTCTime
   where
-    toGraphQL = Type.String . Text.pack . iso8601Show
+    toGraphQL = iso8601ToGraphQL
+
+instance ToGraphQL TimeOfDay
+  where
+    toGraphQL = iso8601ToGraphQL
+
+instance ToGraphQL LocalTime
+  where
+    toGraphQL = iso8601ToGraphQL
 
 -- | Instances of this typeclass can be used to convert GraphQL internal
 -- representation to user-defined type.
@@ -224,8 +246,7 @@ instance FromGraphQL Scientific
 
 instance FromGraphQL Day
   where
-    fromGraphQL (Type.String value') = formatParseM iso8601Format $ Text.unpack value'
-    fromGraphQL _ = Nothing
+    fromGraphQL = fromGraphQLToISO8601
 
 instance FromGraphQL DiffTime
   where
@@ -239,5 +260,12 @@ instance FromGraphQL NominalDiffTime
 
 instance FromGraphQL UTCTime
   where
-    fromGraphQL (Type.String value') = formatParseM iso8601Format $ Text.unpack value'
-    fromGraphQL _ = Nothing
+    fromGraphQL = fromGraphQLToISO8601
+
+instance FromGraphQL TimeOfDay
+  where
+    fromGraphQL = fromGraphQLToISO8601
+
+instance FromGraphQL LocalTime
+  where
+    fromGraphQL = fromGraphQLToISO8601