Hi, I was benchmarking, and Bernouilli has a bit: powers = [2..] : map (zipWith (*) (head powers)) powers Hugs and GHC both see powers :: [[Integer]] and a beautiful CAF. Yhc (and nhc) both see powers :: (Enum a, Num a) => [[a]] and no CAF. This is going to be a severe performance bottleneck! First, can someone with slightly more knowledge check I've got this right. Second, do we "fix" the nofib suite, since the monomorphism restriction is a bit evil and generally to be avoided. Third, do we "fix" nyhc. Fourth, should we care about silly benchmarks. Thanks Neil