"Brettschneider, Matthias" <brettschnei...@hs-albsig.de> wrote:
> Thx for your hints, I played around with them and the performance > gets slightly better. But the major boost is still missing :) > > I noticed, that one real bottleneck seems to be the conversion of the > array back into a list. The interesting part is, if I use the elems > function (Data.Array.Base) the performance is about 4x better then > with my own function. So I thought, I write my own version of elems, > (that just converts a part of the array to a list) and I fall back > into the same performance as my first approach. > > To make a long story short, here is the library code: > elems arr = case bounds arr of > (_l, _u) -> [unsafeAt arr i | i <- [0 .. numElements arr - 1] > > And my version: > boundedElems arr = case bounds arr of > (_l, _u) -> [unsafeAt arr i | i <- [1737 .. 1752]] > > Is there a reason, why the library version is 4 times faster, than > mine? > Uhhhmmm... I've got no idea. But as the list is constructed lazily, you shouldn't expect a real speedup by being lazy manually, anyway. You might want to try the stream-fusion list implementation of lists, or get rid of lists, alltogether. -- (c) this sig last receiving data processing entity. Inspect headers for copyright history. All rights reserved. Copying, hiring, renting, performance and/or quoting of this signature prohibited. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe