Merge branch 'fix-warnings' of https://github.com/23Skidoo/cassava

Author: tibbe

Data/Csv/Conversion.hs

@@ -6,13 +6,16 @@
     FlexibleInstances,
     KindSignatures,
     MultiParamTypeClasses,
-    OverlappingInstances,
     OverloadedStrings,
     Rank2Types,
     ScopedTypeVariables,
     TypeOperators,
     UndecidableInstances
     #-}
+#if __GLASGOW_HASKELL__ < 710
+{-# LANGUAGE OverlappingInstances #-}
+#endif
+
 module Data.Csv.Conversion
     (
     -- * Type conversion
@@ -665,7 +668,11 @@ class ToField a where
     toField :: a -> Field
 
 -- | 'Nothing' if the 'Field' is 'B.empty', 'Just' otherwise.
-instance FromField a => FromField (Maybe a) where
+instance
+#if __GLASGOW_HASKELL__ >= 710
+  {-# OVERLAPPABLE #-}
+#endif
+  FromField a => FromField (Maybe a) where
     parseField s
         | B.null s  = pure Nothing
         | otherwise = Just <$> parseField s