Hallo Evan, If it is really such a performance difference the functions should be exported by all means. (Another work-around might by to inverse the order of the keys, but that'll be unnatural at least for Int keys.) Obviously, I rarely have 1 million elements in my maps. Evan Laforge wrote:
That's one of the things I was asking... how do you obtain toDescList without foldlWithKey? And for me, since since the order of the keys is important (say points in time), the order of the fold matters a great deal. I thought of "reverse . toList". Maybe the folding functions are not needed at all (or only short cuts):
Ah, well if I really didn't care about performance, then I wouldn't use Map at all, just an unsorted [(k, v)]. But it's sort of awkward for the GUI to freeze for a second (yes, it really does take that long) while haskell reverses a 1 million element list just to get the first 3 elements (and does so many times)...
findMax (deleteFinMax) for the highest 3 elements would be faster then.
foldlWithKey f z = foldl (\ b (k, v) -> f b k v) z . toList
This is equivalent to reverse, isn't it? It also takes a second or so (well, once I add a prime of course, without the prime it sends the whole system into OOM molasses).
Yes, but folding is linear anyway (if the whole result is needed). Cheers Christian