gistfile1.txt

class C t where
  data D t

instance forall a. C (Maybe a) where
  data D (Maybe a) where
    D :: forall. a -> D (Maybe a)



Main.hs:6:18: error:
    Not in scope: type variable ‘a’

Main.hs:6:32: error:
    Not in scope: type variable ‘a’