Proposal: Make StateT in mtl lazy

[Neil Mitchell]

Hi

> If we're going to have a strict StateT then it would make sense to have
> a strict State too. Control.Monad.State.Strict perhaps? (and likewise
> for the other mtl monads, where appropriate).

For foldl we have foldl and foldl'. Why not State and State' ? I'm not
a particular fan of changing the imports to get different sets of
behaviours...

Thanks

Nel