There are a few other differences as well. I'm not completely familiar with the ins and outs of Java interfaces, but: * You can instantiate types to classe

There are a few other differences as well. I'm not completely familiar with the ins and outs of Java interfaces, but: * You can instantiate types to classes at any point in time (type definition, class definition, or even orphan instances, though that last category is frowned upon) * Typeclasses indicate typing bounds but do not destroy type information. This means that we can define things like showableId :: Show a => a -> a showableId x = x which allow only showable types to pass but does not destroy type information > showableId (3 :: Int) 3 :: Int > showableId (id :: Int -> Int) !! Type error * Typeclasses can dispatch on *any* type in the signature. This includes the famous "return type polymorphism" but generally means that typeclass resolution involves solving a terminating form of Prolog during typechecking. This means that type information flows forward and backward over judgements and allows for greater inference. * Typeclasses can abstract over higher kinded types. So we can write something like count :: Traversable t => t a -> Int count = getSum . getConst . traverse (const $ Const (Sum 1)) which generically counts the elements in any container instantiating the "interface" Traversable. There's also some even funkier techniques you can use when you start involving MultiParamTypeClasses, FunctionalDependencies, or TypeFamilies.