Proposal: Make StateT in mtl lazy

[Ian Lynagh]

http://hackage.haskell.org/trac/ghc/ticket/1127

Deadline: 28 February 2007.

I propose we make StateT lazy, as I suspect was the intention all along
and as has been discussed (without reaching a conclusion) before.

The patch is simply (in the definition of (>>=)):

hunk ./Control/Monad/State.hs 195
-               (a, s') <- runStateT m s
+               ~(a, s') <- runStateT m s


Thanks
Ian