It's difficult to have a conversation with someone using their own terms for well-established concepts. If I understand you correctly, what you're calling "geo

It's difficult to have a conversation with someone using their own terms for well-established concepts. If I understand you correctly, what you're calling "geometric polymorphism" is usually called structural typing or subtyping, and what you're calling "generic polymorphism" is usually called duck typing. Duck typing isn't amenable to static typechecking, so it's not comparable to Haskell's typeclasses.