I don't know if anyone can help with this; I've checked the FAQs and the bug-reports on SourceForge and found nothing but I'd have thought it might be a common problem for folks migrating from hugs to ghci. I'm used to using hugs in haskell 98 mode but it seems that functions need not be monomorphic in where clauses in that case (is this a departure from the standard?). However, in ghc-5.02.3 for Haskell 98 (without glasgow extensions) it seems that is not the case. I _guessed_ that I need to use the flag -fno-monomorphism-restriction but I don't know whether I've failed to turn it on or if the problem is to be found somewhere else. A related problem I've found is that if I try to specify that flag in a pragma, I get an error message stating that static flags may not be specified in pragmas, and yet the flag is supposed to be dynamic. Here is a simple instance of a program that runs under Hugs but not ghc(i)-5.02.3 : module Test where class Bounded a => Testit a where test1 :: a data Test a = Test {f1::[a], f2::[Char]} class Super a where sup1 :: a -> Maybe a instance (Eq a, Testit a) => Super (Test a) where sup1 (Test{f1=x, f2=y}) = Just Test{f1=x, f2=y} where y' = top y x' = top x top :: [a] -> a top (s:st) = s is it possible to compile this program in ghc-5.02.3? Any advice much appreciated, Matt. -- --------------------------------------------------------------------------- Matt Fairtlough m.fairtlough@dcs.shef.ac.uk Verification and Testing Group Room 115 Department of Computer Science University of Sheffield Regent Court, 211 Portobello Street Sheffield S1 4DP Tel: (0)114-22-21826 UK Fax: (0)114-22-21810 WWW: http://www.dcs.shef.ac.uk/~matt/ ----------------------------------------------------------------------------