ALthough the name is confusing type classes are very much like interfaces in Java: you define a set of operations that you want and then instantiate concrete types to that interface.

The major differences between type classes and interfaces are: * In Java interfaces the interfaced type is restricted to the first argument (the this). In Haskell interfaces the interfaced type can also appear on return values and arguments. * In Java you need to decide what interfaces to implement when you create your class. Haskell allows interfaces to be implemented for previously existing types. * Java allows for subtyping. You can turn a monomorphic program into a polymorphic one just by creating subclasses while in Haskell you would need to rewrite your code to be explicitly polymorphic.