Re: [Haskell-cafe] ST not strict enough?

On Friday 18 November 2011, 11:18:33, Yves Parès wrote:

Instead of rewriting modifySTRef, why not just do :

modifySTRef counter (\x -> let y = x+1 in y `seq` y)

Is there a problem with that?

Yes, y `seq` y is precisely the same as y. a `seq` b means whenever evaluation of b is demanded, also evaluate a (to WHNF). So y `seq` y ~> whenever evaluation of y is demanded, also evaluate y.