Re: [Haskell-cafe] Filtering a big list into the IO monad

Gabriel Sztorc wrote:

Hello,

I want to filter a list with a predicate that returns a IO value, something that filterM is supposed to do. The problem is, filterM overflows the stack for really big lists and I couldn't come up with a simple replacement for filterM that would work for lists of any size (the truth is, I can't come up with anything at all :).

The question is: how to do it? Any help is appreciated.

What is the predicate computing? Does it have side effects? Does the order of evaluation matter? A dangerous solution is to use unsafeInterleaveIO or unsafePerformIO to change your predicate to look like a pure function...