Expert Python Programming - Third Edition

Lambda functions

Lambda functions are a very popular programming concept that is especially profound in functional programming. In other programming languages, lambda function are sometimes known as anonymous functions, lambda expressions, or function literals. Lambda functions are anonymous functions that don't have to be bound to any identifier (variable).

Lambda functions in Python can be defined only using expressions. The syntax for lambda functions is as follows:

lambda <arguments>: <expression>

The best way to present the syntax of lambda functions is through comparing a "normal" function definition with its anonymous counterpart. The following is a simple function that returns the area of a circle of a given radius:

import mathdef ...