Functional programming

In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data.

Description

It uses a declarative programming paradigm: programming is done with expressions.

Depends only on the arguments

In functional code, the output value of a function depends only on the arguments that are input to the function

Therefore calling a function f twice with the same value for an argument x will produce the same result f(x) each time.

Eliminating side effects

Eliminating side effects, i.e. changes in state that do not depend on the function inputs, can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming.

History

Functional programming has its roots in lambda calculus, a formal system developed in the 1930s to investigate:

• Computability
• The Entscheidungsproblem
• Function definition
• Function application
• Recursion

Many functional programming languages can be viewed as elaborations on the lambda calculus.

Logic programming

Another well-known declarative programming paradigm, logic programming, is based on relations.

Imperative programming

In contrast, imperative programming changes state with commands in the source language, the most simple example being assignment.

See also

• Computer program
• Computer programming
• Computer science
• Declarative programming
• Entscheidungsproblem
• Expression (computer science)
• Formal system
• Function (mathematics)
• Lambda calculus
• Logic programming
• Programming paradigm
• Recursion

External links

• Functional programming @ Wikipedia