On 4/11/06, Bulat Ziganshin
Hello Josef,
Monday, April 10, 2006, 9:22:31 PM, you wrote:
Wasn't there some consensus that foldr/build cannot deforest both lists that go into zip?
Umm... I didn't write that. Udo Stenzel did.
that is a typical problem of "two simultaneous control structures" and one it's solution is using coroutines. lazily evaluated lists is of course another solution, but it is not so fast
may be, some lightweight form of coroutines can be used in such situations to perfrom job faster?
I not sure how to understand your comment in the context of the present discussion. As I said before, it is indeed possible to fuse zipWith[1..] with other funcions. The only problem is that we don't know how to do it for all list argument at the same time *within the foldr/build framework*. And since ghc only uses foldr/build at the moment we have to fuse the zipWith family of functions by hand if we want to achieve fusion. Cheers, /Josef