# Lambda calculus

Updated: 03/13/2021 by Computer Hope

First developed by American mathematician Alonzo Church in the 1930s, lambda calculus is a formal system for expressing computation based on the abstraction of functions. It is a foundational principle in mathematical logic. Lambda calculus aims to be a simple system of computation that is an alternative to the "hardware" approach used by Turing machines.

## How is lambda calculus used?

In computer programming, lambda calculus is used to anonymize functions, allowing them to be referred to in the abstract sense. This action makes them first-class objects, allowing them to be operated on like any other entity in the language. For example, an anonymous function can be passed to other functions as a parameter.

One of the first programming languages to use anonymous functions was LISP. The special word lambda in LISP defines a function without giving it a name. For instance, the function x + 2 can be defined anonymously in LISP with the following statement:

`(lambda (x) (+ x 2))`

Anonymous functions are an important part of many modern programming languages, including JavaScript.