[Haskell-cafe] Retrospective type-class extension

[Tony Morris]

We all know that "class (Functor f) => Monad f" is preferable but its
absence is a historical mistake. We've all probably tried once:

instance (Functor f) => Monad f where
    ...

However, is there a type system extension (even proposed but not
implemented) that allows me to retrospectively apply such a notion?

Ideally something like this would be handy if it could somehow be
retrospectively applied:
Monad <- Applicative <- Pointed <- Functor


--
Tony Morris
http://tmorris.net/