[Haskell-cafe] Retrospective type-class extension

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/