The H98 report explicitly says (section 4.3.1) that the type of member functions may only add constraints to the type variables which are local to the member. Hugs accepts this (illegal program from the testsuite) without reporting an error. tests/static/mod39.hs: --!!! Illegal constraints on member funs module M where class C a where f :: Eq a => a If someone can do one of the following, I'll update the testsuite (so it isn't reported as an error) accordingly: 1) Add this to the list of Hugs' non-conformance to the standard. 2) Make this report an error in Haskell 98 mode. 3) Make this report an error in both Haskell 98 and Hugs mode -- Alastair Reid reid@cs.utah.edu http://www.cs.utah.edu/~reid/