|
In computer programming, an anonymous function (also function literal or lambda abstraction) is a function definition that is not bound to an identifier. Anonymous functions are often:〔(【引用サイトリンク】url=http://learnyouahaskell.com/higher-order-functions )〕 # arguments being passed to higher-order functions, or # used for constructing the result of a higher-order function that needs to return a function. If the function is only used once, or a limited number of times, an anonymous function may be syntactically lighter than using a named function. Anonymous functions are ubiquitous in functional programming languages and other languages with first-class functions, where they fulfill the same role for the function type as literals do for other data types. Anonymous functions originate in the work of Alonzo Church in his invention of the lambda calculus in 1936 (prior to electronic computers), in which all functions are anonymous. In several programming languages, anonymous functions are introduced using the keyword lambda, and anonymous functions are often referred to as lambdas or lambda abstractions. Anonymous functions have been a feature of programming languages since Lisp in 1958 and an increasing number of modern programming languages support anonymous functions. Anonymous functions are a form of nested function, in allowing access to variables in the scope of the containing function (non-local variables). This means anonymous functions need to be implemented using closures. Unlike named nested functions, they cannot be recursive without the assistance of a fixpoint operator (also known as an ''anonymous fixpoint'' or ''anonymous recursion'') or binding them to a name. ==Uses== Anonymous functions can be used for containing functionality that need not be named and possibly for short-term use. Some notable examples include closures and currying. Anonymous functions are a matter of style. Using them is never required; anywhere you could use them, you could define a separate normal function that accomplishes the same thing. Some programmers use anonymous functions to encapsulate specific, non-reusable code without littering the code with a lot of little one-line normal functions. In some programming languages, you can define an anonymous function that is custom-tailored to give you exactly (and only) what you want, which is more efficient, elegant, and less error prone to certain operations that involve fixed values. All of the code in the following sections is written in Python 2.x (not 3.x). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Anonymous function」の詳細全文を読む スポンサード リンク
|