{"url":"https://kiririmode.hatenablog.jp/entry/20080401/p2","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fkiririmode.hatenablog.jp%2Fentry%2F20080401%2Fp2\" title=\"\u554f\u984c3-22 (3.3.2  Representing Queues) - \u7406\u7cfb\u5b66\u751f\u65e5\u8a18\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","blog_title":"\u7406\u7cfb\u5b66\u751f\u65e5\u8a18","published":"2008-04-01 00:00:01","author_name":"kiririmode","height":"190","image_url":null,"provider_url":"https://hatena.blog","title":"\u554f\u984c3-22 (3.3.2  Representing Queues)","width":"100%","type":"rich","version":"1.0","provider_name":"Hatena Blog","author_url":"https://blog.hatena.ne.jp/kiririmode/","categories":["SICP"],"blog_url":"https://kiririmode.hatenablog.jp/","description":"\u30af\u30ed\u30fc\u30b8\u30e3\u3067\u30ad\u30e5\u30fc\u3092\u5b9f\u73fe\u3059\u308b\uff0e (define (make-queue) (let ((front-ptr '()) (rear-ptr '())) (define (set-front-ptr! item) (set! front-ptr item)) (define (set-rear-ptr! item) (set! rear-ptr item)) (define (empty-queue?) (null? front-ptr)) (define (front-queue) (if (empty-queue?) (error \"FRONT called with an empty que\u2026"}