Editing Nested function (section)

{{Short description|A named function defined within a function}}

In [[computer programming]], a '''nested function''' (or '''nested procedure''' or '''subroutine''') is a [[identifier|named]] [[subroutine|function]] that is defined within another, enclosing, block and is [[lexically scoped]] within the enclosing block {{endash}} meaning it is only callable by name within the body of the enclosing block and can use [[identifiers]] declared in outer [[Block (programming)|blocks]], including outer functions. The enclosing block is typically, but not always, another function.
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[[Programming language]] support for nested functions varies. With respect to [[structured programming]] languages, it is supported in some outdated languages such as [[ALGOL]], [[Simula 67]] and [[Pascal (programming language)|Pascal]] and in the commonly used [[JavaScript]]. It is commonly supported in [[dynamic language|dynamic]] and [[functional language|functional]] languages.
However, it is not supported in some commonly used languages including standard [[C language|C]] and [[C++]].

Other programming technologies provide similar benefit. For example, a [[Lambda function (computer programming)|lambda function]] also allows for a function to be defined inside of a function (as well as elsewhere) and allows for similar data hiding and encapsulation. Notably, a lambda function has no name (is anonymous) and therefore cannot be called by name and has no visibility aspect.