If by "generics", you are referring to the sort of parametric polymorphism that you have in .NET and Java, then no, you don't use functors for that. # let

If by "generics", you are referring to the sort of parametric polymorphism that you have in .NET and Java, then no, you don't use functors for that. # let foo x = x;; val foo : 'a -> 'a You need to use functors if you want higher-kinding, but they're generally useful beyond that, and I wish more typed languages had an SML style module system. F# doesn't have one, and has always had a punier type system.