vallog: Re: schemeで全dataを+するのを知りたいです、か？

2010/09/22

私もやってみました。

mysum

	;; http://d.hatena.ne.jp/yad-EL/20100921/p1
	;; (mysum 20) => error
	;; (mysum '()) => 0
	;; (mysum '(1 2 3)) => 6
	;; (mysum '((1 2) ((3)) (4 (5)))) => 15

	(define (tree-fold proc seed tree)
	(if (list? tree)
	(fold (lambda (e acc)
	(if (list? e)
	(tree-fold proc acc e)
	(proc e acc))) seed tree)
	(error "argument must be a list, but got")))

	(define (mysum tree)
	(tree-fold + 0 tree))

	(mysum 20)
	;; *** ERROR: argument must be a list, but got
	(mysum '())
	;; 0
	(mysum '(1 2 3))
	;; 6
	(mysum '((1 2) ((3)) (4 (5))))
	;; 15

view raw mysum.scm hosted with ❤ by GitHub

mytrans

	;; http://d.hatena.ne.jp/yad-EL/20100921/p1
	;; (mytrans 1) => error
	;; (mytrans '()) => 0
	;; (mytrans '(1 2 3)) => (one two three)
	;; (mytrans '((1 2) ((3)) (4 (5 6)))) => ((one two) ((three)) (four (five six)))

	(define (tree-map proc tree)
	(map (lambda (e)
	(if (list? e)
	(tree-map proc e)
	(proc e))) tree))

	(define table '(zero one two three
	four five six seven
	eight nine ten))

	(define (mytrans tree)
	(cond ((not (list? tree))(error "argument must be a list, but got"))
	((null? tree) 0)
	(else (tree-map (lambda (e)
	(list-ref table e)) tree))))


	(mytrans 1)
	;; *** ERROR: argument must be a list, but got
	(mytrans '())
	;; 0
	(mytrans '(1 2 3))
	;; (one two three)
	(mytrans '((1 2) ((3)) (4 (5 6))))
	;; ((one two) ((three)) (four (five six)))

view raw mytrans.scm hosted with ❤ by GitHub

myfind

view raw myfind.scm hosted with ❤ by GitHub

vallog