On Thu, Jul 15, 2010 at 3:13 AM, Michael Snoyman <michael@snoyman.com> wrote:
> You could also use type families for this, but I believe you cannot express
> the "Show" superclass:
> class MyClass a where
>     type MyResult a
>     fn :: a -> MyResult a

I guess this works:

class Show (MyResult a) => MyClass a where

 type MyResult a
 fn :: a -> MyResult a