Such as Identity?Well in: inv :: (Monad m, ...) => m a -> m () inv m = ... I don't mind that there are more constraints on 'm' than just Monad
class Monad m => MonadInv m where inv :: m a -> m () With this constraint you certainly can have your "inv". _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
