Re: ConstraintKinds and default associated empty constraints

On 22 December 2011 09:31, Simon Peyton-Jones wrote:

What about

class Functor f where    type C f :: * -> Constraint    type C f = ()

After all, just as (Ord a, Show a) is a contraint, so is ().

But there's a kind mis-match there. `C f` should have kind `* -> Constraint` but () has kind *. Or do I have to enable some language extension to make this work? Thanks, Bas