So I want to have a polymorphic Collection type, just because.

class Collection c e | c -> e where empty :: c put :: c -> e -> c

data SomeCollection e = forall c . Collection c e => MakeSomeCollection c

Hugs (February 2000) doesn't like it. It says Variable "e" in constraint is not locally bound I feel that e *is* bound, sort of, because c is bound and there's a fundep c->e. Who's wrong, me or Hugs? The following things work as expected:

data IntCollection = forall c . Collection c Int => MakeIntCollection c data AnyCollection = forall c e . Collection c e => MakeAnyCollection c

Regards -- anatoli __________________________________________________ Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/