Having looked into Ceylon and thought about this a little more... Ceylon's subtyping is the big thing that is coming to mind right now that makes me prefer Has

Having looked into Ceylon and thought about this a little more... Ceylon's subtyping is the big thing that is coming to mind right now that makes me prefer Haskell's type system. The purpose of a type system in my mind is to prevent bad programs from being written. But when you combine subtyping with generics you get a problem. Nothing keeps you from looking for an Employee in a Set<Int> because both Employee and Int are a subtype of Object and the covariant use of Set<Int> can be promoted to Set<Object>. But that's a nonsensical thing to do and should obviously be a type error. This kind of thing comes up a lot in practice and is a place where Haskell's type system is safer.