[Haskell-cafe] List algorithm

Hello, is there an efficient algorithm that takes two positive numbers n and m and that computes all lists l of numbers 0sum l == m) (powerSet [1..n]) would do the job, however I am looking for a more efficient approach. Help is greatly appreciated, even a google search term would be fine :-) I really hope for a polynomial algorithm although I am not very optimistic about this. Ciao, Steffen