Re: [Haskell] Forcing Type Class Equality

Hi John,

NB

the essence what I am trying to do is to define a proxy class Foo for class Ba1 I would have thought that something as simple as the following would have worked ??

class Ba1 a where dosomething :: a -> IO ()

ba1 :: Ba1 a => a -> IO () ba1 x = dosomething x

instance Ba1 Int where dosomething x = print x

instance Ba1 Char where dosomething x = print x

what I wish to do is declare another function

If you implement the proxy function like below, it should work: class Ba1 a => Foo a where proxy :: a -> IO () proxy = ba1 I've made Foo a subclass of Ba1 with a member function proxy and a default implementation. I hope this will help you further.. Grt PS Use the haskell-cafe list next time for this kind of questions.