In [[programming languages]], '''ad-hoc polymorphism'''<ref>C. Strachey, Fundamental concepts in programming languages. Lecture notes for International Summer School in Computer Programming, Copenhagen, August 1967</ref> is a kind of [[polymorphism (computer science)|polymorphism]] in which polymorphic functions can be applied to arguments of different types, because a polymorphic function can denote a number of distinct and potentially heterogeneous implementations depending on the type of argument(s) to which it is applied. It is also known as [[function overloading]] or [[operator overloading]]. The term [[ad hoc]] in this context is not intended to be pejorative; it refers simply to the fact that this type of polymorphism is not a fundamental feature of the [[type system]]. This is in contrast to [[parametric polymorphism]], in which polymorphic functions are written without mention of any specific type, and can thus apply a single abstract implementation to any number of types in a transparent way. This classification was introduced by [[Christopher Strachey]] in 1967.
