[Haskell-cafe] ST not strict enough?
jason.dusek at gmail.com
Fri Nov 18 05:57:34 CET 2011
2011/11/16 Johan Tibell <johan.tibell at gmail.com>:
> On Wed, Nov 16, 2011 at 2:23 PM, Jason Dusek <jason.dusek at gmail.com> wrote:
>> Tried a modifySTRef' defined this way:
>> modifySTRef' ref f = do
>> val <- (f $!!) <$> readSTRef ref
>> writeSTRef ref (val `seq` val)
>> ...but there was no change in memory usage.
> Why not just
> modifySTRef :: STRef s a -> (a -> a) -> ST s ()
> modifySTRef ref f = do
> x <- readSTRef ref
> writeSTRef ref $! f x
> (Note that I didn't check if modifySTRef was actually a problem in this
I just didn't want to miss an opportunity to put in extra
strictness annotations! School of redundancy school.
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