type FunDep a = ([a],[a]) -- e.g. class C a b c | a b -> c, a c -> b where ...
-- Here fun-deps are [([a,b],[c]), ([a,c],[b])]
-type ClassOpItem = (Id, DefMeth Id)
+type ClassOpItem = (Id, DefMeth Name)
-- Selector function; contains unfolding
-- Default-method info