tmurata https://blog.hatena.ne.jp/tmurata/ tmurataの日記 https://tmurata.hatenadiary.org/ SICP unless の実装。unlessをifに変換するように実装する 追加する手続き (define (unless? exp) (tagged-list? exp 'unless)) (define (unless-predicate exp) (cadr exp)) (define (unless-consequent exp) (caddr exp)) (define (unless-alternative exp) (if (not (null? (cdddr exp))) (cadddr exp) 'false)) ;; make-ifはcond->ifで定義済 (define (unl… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Ftmurata.hatenadiary.org%2Fentry%2F20100423%2F1272021811" title="SICP問題4.26 - tmurataの日記" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> Hatena Blog https://hatena.blog 2010-04-23 20:23:31 rich https://tmurata.hatenadiary.org/entry/20100423/1272021811 1.0 100%