syntax-rules: if

• Scheme 入門 15. 構文の定義

マクロとは式の変換です。 

	;; if
	;; http://www.shido.info/lisp/scheme_syntax.html
	(define-macro (my-if pred then else)
	`(cond (,pred ,then)
	(else ,else)))
	(display (my-if (odd? 1)
	"yes"
	"no"))
	(macroexpand '(my-if (odd? 1)
	"yes"
	"no"))
	; -> (cond ((odd? 1) "yes") (else "no"))

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