Please forgive me if I'm still mentally contaminated by the OO way of seeing (and discussing) the universe, but I'm trying to figure out how to "inherit an interface" from a multi-parameter type class. I have a Graph class that's parameterisable by Node and Edge type: class (Node a, Edge b) => Graph a b where (lots of stuff that you can do with Graph a b) Now, I'd like to build a FooGraph on top of this that adds additional capabilities: class (Graph a b) => FooGraph a b where (lots of additional stuff) but this isn't allowed (kind mismatch). Of couse, I can do: class (Node a, Edge b) => FooGraph a b but this means that I have to manually replicate the Graph a b operations in the FooGraph a b class definition, which is (a) work that the machine should (?) be able to do for me, and (b) fragile. Any pointers / wisdom would be very much appreciated. - Derek