Hi, Some of the nofib suite are messed up by Yhc/nhc because of the monomorphism restriction. Take imaginary/bernouilli as an example: powers = [2..] : map (zipWith (*) (head powers)) powers Hugs and GHC both see powers :: [[Integer]] and a CAF. Yhc (and nhc) both see powers :: (Enum a, Num a) => [[a]] and no CAF. This completely destroys the performance in Yhc/nhc. Since this is not so much a performance aspect but a compiler bug, based on a feature whose future in Haskell' is as yet unclear, perhaps it would be wise to patch nofib to include an explicit type signature where this matters. I am happy to send in a patch (or just apply it) - but I have no idea who "maintains" the suite. I've CC'd those people who make substantial use of the nofib suite. Thanks Neil