[Haskell-cafe] newbie type signature question

[Brock Peabody]

Please excuse my newbiness, but in this snippet:


   data (Monad m) => DataType m = DataType { f :: Char -> m () }
                  
   test_function :: (Monad m) => DataType m -> m ()
                    ^^^^^^^^^^^^
   test_function d =  f d 'C'



Why is "(Monad m) =>" required, when the definition of DataType already
implies it?  Is there an easier way to do this or will I have to have it
in all signatures containing DataType?

Thanks,

Brock