|
In computer science, syntactic sugar is syntax within a programming language that is designed to make things easier to read or to express. It makes the language "sweeter" for human use: things can be expressed more clearly, more concisely, or in an alternative style that some may prefer. For example, many programming languages provide special syntax for referencing and updating array elements. Abstractly, an array reference is a procedure of two arguments: an array and a subscript vector, which could be expressed as get_array(Array, vector(i,j)). Instead, many languages provide syntax like Array() . Similarly an array element update is a procedure of three arguments, something like set_array(Array, vector(i,j), value), but many languages provide syntax like Array() = value.Specifically, a construct in a language is called syntactic sugar if it can be removed from the language without any effect on what the language can do: functionality and expressive power will remain the same. Language processors, including compilers, static analyzers, and the like, often expand sugared constructs into more fundamental constructs before processing, a process sometimes called "desugaring". == Origins == The term ''syntactic sugar'' was coined by Peter J. Landin in 1964 to describe the surface syntax of a simple ALGOL-like programming language which was defined semantically in terms of the applicative expressions of lambda calculus, centered around lexically replacing λ with "where". Building on Landin's distinction between essential language constructs and syntactic sugar, in 1991, Matthias Felleisen proposed a codification of "expressive power" to align with "widely held beliefs" in the literature. He defined "more expressive" to mean that without the language constructs in question, a program would have to be completely reorganized. Later programming languages, such as CLU, ML and Scheme, extended the term to refer to syntax within a language which could be defined in terms of a language core of essential constructs; the convenient, higher-level features could be "desugared" and decomposed into that subset.〔Barbara Liskov, "A History of CLU", MIT Laboratory for Computer Science Technical Report 561 (1993)〕 This is, in fact, the usual mathematical practice of building up from primitives. 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「syntactic sugar」の詳細全文を読む スポンサード リンク
|