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Emacs Lisp is a dialect of the Lisp programming language used by the GNU Emacs and XEmacs text editors (which this article will refer to collectively as "Emacs"). It is used for implementing most of the editing functionality built into Emacs, the remainder being written in C (as is the Lisp interpreter itself). Emacs Lisp is also referred to as Elisp, although there is also an older, unrelated Lisp dialect with that name. Users of Emacs commonly write Emacs Lisp code to customize and extend Emacs. Other options include the "Customize" feature that's in GNU Emacs since version 20. This provides a set of preference pages and when the user saves their preferences, Customize writes the necessary Emacs Lisp code to the user's config file. Emacs Lisp can also function as a scripting language, much like the Unix Bourne shell or Python, by calling Emacs in "batch mode". In this way it may be called from the command line or via an executable file, and its editing functions, such as buffers and movement commands are available to the program just as in the normal mode. ==Compared to other Lisp dialects== In terms of features, it is closely related to the Maclisp dialect, with some later influence from Common Lisp.〔"GNU Emacs Lisp is largely inspired by Maclisp, and a little by Common Lisp. If you know Common Lisp, you will notice many similarities. However, many features of Common Lisp have been omitted or simplified in order to reduce the memory requirements of GNU Emacs. Sometimes the simplifications are so drastic that a Common Lisp user might be very confused. We will occasionally point out how GNU Emacs Lisp differs from Common Lisp." — from the "History" section of the "Introduction" to the Emacs Lisp Manual, as of Emacs 21〕 It supports imperative and functional programming methods. Richard Stallman chose Lisp as the extension language for his rewrite of Emacs (the original used TECO as its extension language) because of its powerful features, including the ability to treat functions as data. Unlike Common Lisp, Scheme existed at the time Stallman was rewriting Gosling Emacs into GNU Emacs, but he chose not to use it because of its comparatively poor performance on workstations, and he wanted to develop a dialect which he thought would be more easily optimized.〔"So the development of that operating system, the GNU operating system, is what led me to write the GNU Emacs. In doing this, I aimed to make the absolute minimal possible Lisp implementation. The size of the programs was a tremendous concern. There were people in those days, in 1985, who had one-megabyte machines without virtual memory. They wanted to be able to use GNU Emacs. This meant I had to keep the program as small as possible." — from ("My Lisp Experiences and the Development of GNU Emacs" )〕 The Lisp dialect used in Emacs differs substantially from the more modern Common Lisp and Scheme dialects commonly used for applications programming. For example: Emacs Lisp uses dynamic rather than lexical scope by default (see below). That is, a function can reference local variables in the scope it's called from, but not in the scope where it was defined. 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「emacs lisp」の詳細全文を読む スポンサード リンク
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