{"title":"\u4e8c\u5206\u63a2\u7d22\u6728","url":"https://tech-blog.pocket7878.com/entry/2012/10/31/104246","width":"100%","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Ftech-blog.pocket7878.com%2Fentry%2F2012%2F10%2F31%2F104246\" title=\"\u4e8c\u5206\u63a2\u7d22\u6728 - Let&#39;s write \u03b2\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","version":"1.0","blog_url":"https://tech-blog.pocket7878.com/","author_url":"https://blog.hatena.ne.jp/Pocket7878_dev/","image_url":null,"type":"rich","height":"190","provider_name":"Hatena Blog","author_name":"Pocket7878_dev","provider_url":"https://hatena.blog","blog_title":"Let's write \u03b2","categories":["Lisp"],"published":"2012-10-31 10:42:46","description":"(defun kv (key val) (cons key val)) (defun tree (val left right) (list val left right)) (defun tree->val (tree) (car tree)) (defun tree->left (tree) (cadr tree)) (defun tree->right (tree) (caddr tree)) (defun leafp (tree) (and (null (tree->left tree)) (null (tree->right tree)))) (defun walk (tree) (\u2026"}