[Haskell-cafe] forLoop + strict State monad is much faster than foldl'

[Niklas Hambüchen]

Interestingly, the discrimination against Word32 does not end here:

When compiling with -fllvm
(http://htmlpreview.github.io/?https://github.com/nh2/loop/blob/master/results/bench-foldl-and-iorefs-are-slow-llvm.html),
we can see that the forLoop + strict State monad is completely compiled
away to a no-op for Int, but not for Word32.