syntax-rules: dotimes

• （PDF）Advanced Scheme Techniques - Some Naughty Bits

	;; dotimes
	(define-syntax dotimes
	(syntax-rules ()
	((_ n body ...)
	(do ((i n (- i 1)))
	((not (< 0 i)))
	body ...))))
	(dotimes 5
	(display "hello")
	(print "world"))
	;; helloworld
	;; helloworld
	;; helloworld
	;; helloworld
	;; helloworld
	;; #t
	(define-syntax dotimes
	(syntax-rules ()
	((_ n body ...)
	(let loop ((i n))
	(when (< 0 i)
	body ...
	(loop (- i 1)))))))
	(dotimes 5
	(print "H")
	(print "l")
	(print "l")
	(print "o"))
	;; H
	;; l
	;; l
	;; o
	;; H
	;; l
	;; l
	;; o
	;; H
	;; l
	;; l
	;; o
	;; H
	;; l
	;; l
	;; o
	;; H
	;; l
	;; l
	;; o
	;; #<undef>

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