15 lines
2.9 KiB
HTML
15 lines
2.9 KiB
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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>cdr</title><link rel="stylesheet" href="../../jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="../index.html" title="The Jargon File"/><link rel="up" href="../C.html" title="C"/><link rel="previous" href="CDA.html" title="CDA"/><link rel="next" href="chad.html" title="chad"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">cdr</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="CDA.html">Prev</a><EFBFBD></td><th width="60%" align="center">C</th><td width="20%" align="right"><EFBFBD><a accesskey="n" href="chad.html">Next</a></td></tr></table><hr/></div><dt><a id="cdr"/><dt xmlns="" id="cdr"><b>cdr</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="pronunciation">/ku<6B>dr/</span>, <span xmlns="http://www.w3.org/1999/xhtml" class="pronunciation">/kuh<75>dr/</span>, <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">vt.</span></dt></dt><dd><p> [from LISP] To skip past the first item from a list of things
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(generalized from the LISP operation on binary tree structures, which
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returns a list consisting of all but the first element of its argument).
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In the form <span class="firstterm">cdr down</span>, to trace down a
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list of elements: “<span class="quote">Shall we cdr down the agenda?</span>” Usage:
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silly. See also <a href="../L/loop-through.html"><i class="glossterm">loop through</i></a>.</p></dd><dd><p>Historical note: The instruction format of the IBM 704 that hosted
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the original LISP implementation featured two 15-bit fields called the
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<span class="firstterm">address</span> and <span class="firstterm">decrement</span> parts. The term <span class="firstterm">cdr</span> was originally <span class="firstterm">Contents of Decrement part of Register</span>.
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Similarly, <span class="firstterm">car</span> stood for <span class="firstterm">Contents of Address part of Register</span>.</p><p>The cdr and car operations have since become bases for formation of
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compound metaphors in non-LISP contexts. GLS recalls, for example, a
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programming project in which strings were represented as linked lists; the
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get-character and skip-character operations were of course called CHAR and
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CHDR.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="CDA.html">Prev</a><EFBFBD></td><td width="20%" align="center"><a accesskey="u" href="../C.html">Up</a></td><td width="40%" align="right"><EFBFBD><a accesskey="n" href="chad.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CDA<EFBFBD></td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"><EFBFBD>chad</td></tr></table></div></body></html>
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