Higher-order functions

Recursion and Higher-order Functions - slide 13 : 35

A higher-order function accepts functions as arguments and/or is able to return a function as its result

A higher-order language supports higher-order functions and allows functions to be constituents of data structures

The order of data
- Order 0: Non function data
- Order 1: Functions with domain and range of order 0
- Order 2: Functions with domain and range of order 1
- Order k: Functions with domain and range of order k-1

Functions of order i, i >= 2, are called higher-order functions