Generic function

In certain systems for object-oriented programming such as the Common Lisp Object System and Dylan programming language, a generic function is an entity made up of all methods having the same name.

Generic functions correspond roughly to what Smalltalk calls messages; but when a generic function is called, method dispatch occurs on the basis of all arguments, not just a single privileged one. See under multiple dispatch for more. This is also known as a multimethod.

An other, completely separate definition of generic function is a function that uses parametric polymorphism. This is the definition used when working with a language like Ocaml. An example of a generic function is id: a->a let id a = a which takes an argument of any type and returns something of that same type.