hello, program: sieve :: [Int] -> [Int] sieve (x:xs) = x: sieve [c|c<-xs, mod c x > 0] and then run: sieve [2..] breaks after number 16477 with an 'Illegal instruction' (the mac os X native signal) and hugs quits. Now, I expected an 'out of memory' or a 'number overflow' or 'stack overflow' or something thelike, but not this, this implies a buffer overrun or something. I am not sure how anyways, just reporting, my hardware is a white iBook 2002 600Mhz running mac os X 10.2.4 the software used is Hugs 98 Version November 2002. -Onne