Higher-order function
infogalactic Higher-order function
In mathematics and computer science, a higher-order function (also functional, functional form or functor; not to be confused with the functor concept in category theory) is a function that does at least one of the following:
- takes one or more functions as arguments,
- returns a function as its result.
All other functions are first-order functions.
In the untyped lambda calculus, all functions are higher-order; in a typed lambda calculus, from which most functional programming languages are derived, higher-order functions are values with types of the form 
.