[Haskell-cafe] Inheritance constraints

[Miguel Mitrofanov]

Hi cafe!

The ConstraintKinds extension makes it possible to create classes of classes, like this:

class F c where cfmap :: c f => (a -> b) -> f a -> f b
instance F Functor where cfmap = fmap
instance F Monad where cfmap = liftM

So, basically we are saying that "c" is a class that has some special properties.

Is it possible to express the property "c is a subclass of a specific class d"? Like
class F c where Functor f => c f