{"id":230,"date":"2022-08-30T14:57:53","date_gmt":"2022-08-30T14:57:53","guid":{"rendered":"https:\/\/unknownerror.org\/index.php\/2013\/08\/31\/why-no-error-about-undefined-variable-is-raised-in-lisp-while-setq-record-and-share-programming-errors\/"},"modified":"2022-08-30T14:57:53","modified_gmt":"2022-08-30T14:57:53","slug":"why-no-error-about-undefined-variable-is-raised-in-lisp-while-setq-record-and-share-programming-errors","status":"publish","type":"post","link":"https:\/\/unknownerror.org\/index.php\/2022\/08\/30\/why-no-error-about-undefined-variable-is-raised-in-lisp-while-setq-record-and-share-programming-errors\/","title":{"rendered":"Why no error about undefined variable is raised in LISP while setq()?-Record and share programming errors"},"content":{"rendered":"<ul>\n<li>\n<p>When a datum is quoted, nothing within is evaluated. For example:<\/p>\n<pre><code>foo\n<\/code><\/pre>\n<p>evaluates to the value bound to the identifier <code>foo<\/code>, whereas<\/p>\n<pre><code>'foo\n<\/code><\/pre>\n<p>or<\/p>\n<pre><code>(quote foo)\n<\/code><\/pre>\n<p>evaluates to the symbol <code>foo<\/code>.<\/p>\n<p>Likewise,<\/p>\n<pre><code>(+ 1 2 3)\n<\/code><\/pre>\n<p>evaluates to 6, whereas<\/p>\n<pre><code>'(+ 1 2 3)\n<\/code><\/pre>\n<p>or<\/p>\n<pre><code>(quote (+ 1 2 3))\n<\/code><\/pre>\n<p>evaluate to a list with four elements: the symbol <code>+<\/code>, and the numbers 1, 2, and 3. In particular, the <code>+<\/code> is not evaluated.<\/p>\n<p>Similarly, your <code>name<\/code> and <code>mode<\/code>, both being within the quoted datum, are not treated as identifiers, but as symbols. They are not evaluated.<\/p>\n<\/li>\n<li>\n<p>Look at C-h v ibuffer-saved-filter-groups. It explains about this variables further. It is an alist variable. According to documents, it should look like ((&#8220;STRING&#8221; QUALIFIERS) (&#8220;STRING&#8221; QUALIFIERS) &#8230;) Now QUALIFIERS is a LIST of the same form as `ibuffer-filtering-qualifiers&#8217;. It is a LIST like (SYMBOL . QUALIFIER).<\/p>\n<\/li>\n<\/ul>\n<p id=\"rop\"><small>Originally posted 2013-08-31 05:20:15. <\/small><\/p>","protected":false},"excerpt":{"rendered":"<p>When a datum is quoted, nothing within is evaluated. For example: foo evaluates to the value bound to the identifier foo, whereas &#8216;foo or (quote foo) evaluates to the symbol foo. Likewise, (+ 1 2 3) evaluates to 6, whereas &#8216;(+ 1 2 3) or (quote (+ 1 2 3)) evaluate to a list with [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-230","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/230","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=230"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/230\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=230"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=230"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=230"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}