MonadRef class or the like?

[Hal Daume III]

Is there any particular reason there isn't a class for monads for which
things like IORef/STRef exist?  I suppose the naive approach would require
functional dependencies + mp typeclasses[1], which is a decent reason :),
but has anyone come up with something that doesn't require extensions?

[1] i'm thinking of something like:

class MonadRef m r | m -> r, r -> m where
  newRef :: a -> m (r a)
  readRef :: r a -> m a
  writeRef :: r a -> a -> m ()
  updateRef :: (a -> a) -> r a -> m ()

i think you need the FD in both directions (certainly you need m -> r); i
think the latter would serve to disambiguate things like readRef (having
not actually implemented this, though, i don't know).

 - Hal

--
Hal Daume III

 "Computer science is no more about computers    | hdaume@isi.edu
  than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume