Add MonadFix?

[treeowl]

Haskell has a class

class Monad m => MonadFix m where
  mfix :: (a -> m a) -> m a

It should be possible to do something similar in PureScript. I'm not sure which of these types makes more sense:

  mfix1 :: (Lazy a -> m a) -> m a
  mfix2 :: (Lazy a -> m (Lazy a)) -> m (Lazy a)