Functions exist in every higher-level programming language. However, the functional approach in software development deals with functions in a very particular way.
A functionally programmed program is made up of a string of function calls, where each program section can be understood as a function. In functional programming, the functions can take on different forms. For example, they can be linked to one another like data or be used in the form of parameters. In addition, they can subsequently be used as function results. Conversely, the paradigm leads to there being no independent assignment of values.
This subsidiary form of declarative programming is very important for computer science in general – and at the same time can be used for a wide range of specific purposes. The special handling of functions enables programmers using the functional method to create and use extensive calculation rules made up of functions.