What Haskell calls a "class" is what Java calls an "interface". What Haskell calls an "instance" of an interface is what Java would call a class implementing t

What Haskell calls a "class" is what Java calls an "interface". What Haskell calls an "instance" of an interface is what Java would call a class implementing that interface. `Num`, then, is a Haskell class (Java interface). The `Num` class will have a bunch of what Java would call "default methods". Now, the "instance" of `Num` defined here has only a few methods defined, but the other default methods of `Num` will use those. So if `Num` has a `^` defined in terms of ``, and you define an instance of `Num` that defines ``, then you get `^` for free if you don't implement it.