Defining an instance of "concatenable" (eg, Monoid) for some type in Haskell is pretty much isomorphic to overloading some free function (or operator) on some t

Defining an instance of "concatenable" (eg, Monoid) for some type in Haskell is pretty much isomorphic to overloading some free function (or operator) on some type in C++. It's the same "amount of polymorphism" either way, namely ad-hoc polymorphism.