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An anaphoric macro is a type of programming macro that deliberately captures some form supplied to the macro which may be referred to by an ''anaphor'' (an expression referring to another). Anaphoric macros first appeared in Paul Graham's ''On Lisp''〔(Chapter 6 ) of Let over Lambda〕 and their name is a reference to linguistic anaphora〔—the use of words as a substitute for preceding words. ==Examples== The loop macro in ANSI Common Lisp is anaphoric in that it binds it to the result of the test expression in a clause.〔(22. LOOP for Black Belts ) from Practical Common Lisp〕〔(What would be an example of an anaphoric conditional in Lisp? ) on StackOverflow〕 Here is an example that sums the value of non-nil elements, where ''it'' refers to the values of elements that do not equal nil: (loop for element in '(nil 1 nil 2 nil nil 3 4 6) when element sum it) ;; ⇒ 16 Here ''it'' is bound to the output of (and (> number 3) number) when true, collecting numbers larger than 3:〔(6.1.8.1 Examples of clause grouping ) from the Common Lisp HyperSpec〕 (loop for number from 1 to 6 when (and (> number 3) number) collect it) ; IT refers to (and (> number 3) number). ;; ⇒ (4 5 6) 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「Anaphoric macro」の詳細全文を読む スポンサード リンク
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