Brian,
I read the easy parts of the "Associated Types with Class" and "Associated Type Synonyms" papers. An associated type synonym seems to kind of work similarly to a restricted form of class. In what way are the two following examples different?
-- define a class with a type synonym, and a set of operations class A a where type B b foo :: a -> B b
instance A Int where type B = Bool foo = (==0)
-- define two classes, and an function that . class A a, B b where foo :: a -> b
instance A Int, B Bool where foo = (==0)
It is more like -- using multi-parameter type classed with functional dependencies (as found, for example, in GHC): class A a b | a -> b where foo :: a -> b instance A Int Bool where foo = (== 0) Cheers, Stefan