Function Composition with Python

Introduction

Function composition is a technique used in functional programming to combine two or more functions to form a new function. In Python, we can use the functools.reduce() function to perform right-to-left function composition.

Compose Functions

Write a function called compose(*fns) that accepts one or more functions as arguments and returns a new function that is the result of composing the input functions from right to left. The last (rightmost) function can accept one or more arguments; the remaining functions must be unary.

from functools import reduce

def compose(*fns):
  return reduce(lambda f, g: lambda *args: f(g(*args)), fns)

add5 = lambda x: x + 5
multiply = lambda x, y: x * y
multiply_and_add_5 = compose(add5, multiply)
multiply_and_add_5(5, 2) ## 15

Summary

In this challenge, you learned how to use the functools.reduce() function to perform right-to-left function composition in Python. You also wrote a function called compose() that accepts one or more functions as arguments and returns a new function that is the result of composing the input functions from right to left.