[Haskell-beginners] Understanding program stack usage
patrick.leboutillier at gmail.com
Wed Apr 27 20:25:22 CEST 2011
I tried the $! bit, but I get the same result. I guess there's another
On Wed, Apr 27, 2011 at 11:20 AM, Felipe Almeida Lessa
<felipe.lessa at gmail.com> wrote:
> On Wed, Apr 27, 2011 at 11:52 AM, Patrick LeBoutillier
> <patrick.leboutillier at gmail.com> wrote:
>> How do I figure out why the program needs a lot of stack?
> Usually it is because you are building a large thunk.
>> Also, is there an easy way to increace performance?
> Getting rid of the thunks should increase performance as well.
> I've had just a quick look on your code, but here are some suggestions:
>> record :: (Ord n) => n -> Distrib n -> Distrib n
>> record n (Distrib m rs) = Distrib (M.alter f slot m) rs
>> where f (Just n) = Just $ n + 1
>> f Nothing = Just 1
>> slot = findSlot n rs
>> findSlot x (r@(Range a b):rs)
>> | x >= a && x < b = r
>> | otherwise = findSlot x rs
>> findSlot x  = OutOfBounds
> Try changing "Just $ n + 1" to "Just $! n + 1". It is possible that
> this change alone removes the leak (it is the only obvious leak I'm
> seeing right now).
> Also, for findSlot you may want to do a binary search, but that isn't
> related to the leak at all.
Rosemère, Québec, Canada
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