In ghc-5.00.1, "seq (2/0) 3" gives 3. Should it not give error. Hugs does.

I suspect that Hugs is wrong and ghc is right in this case. Certainly nhc98 and hbc agree with ghc's behaviour. seq x y means evaluate x to whnf and throw away the result, returning y instead. It shouldn't matter whether the result of x is bottom. Regards, Malcolm