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<html><head><title>XLISP sort</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>sort</h1>
<hr>
<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
<td><nobr>Type:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>function (subr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xllist.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(sort <i>list test</i>)</dt>
<dd><i>list</i> - a list containing elements to be sorted<br>
<i>test</i> - the test to use for the sort<br>
returns - the sorted list</dd>
</dl>
<h2>Description</h2>
<p>The 'sort' function sorts the 'list' using the 'test' to order the
list. The 'sort' function is destructive and modifies the 'list'.</p>
<h2>Examples</h2>
<pre class="example">
(setq a '(3 1 4 1 5 9 6 7)) <font color="#008844">; returns (3 1 4 1 5 9 6 7)</font>
(sort a '<) <font color="#008844">; returns (1 1 3 4 5 6 7 9)</font>
(print a) <font color="#008844">; returns (1 1 3 4 5 6 7 9)</font>
<font color="#008844">; notice that A is modified</font>
(sort a '>) <font color="#008844">; returns (9 7 6 5 4 3 1 1)</font>
(sort '("a" "bar" "foo") 'string>) <font color="#008844">; returns ("foo" "bar" "a")</font>
</pre>
<p><div class="box">
<p><b>XLISP Bug</b></p>
<p>Nyquist 'sort' returns the proper value, but improperly modifies the
symbol or the actual 'list', for example:</p>
<pre class="example">
(setq a '(3 1 4 1 5 9 6 7)) => (3 1 4 1 5 9 6 7)
(sort a '<) => (1 1 3 4 5 6 7 9) <font color="#008844">; OK</font>
a => (3 4 5 6 7 9) <font color="#AA0000">; BUG</font>
</pre>
<p>But this way it works:</p>
<pre class="example">
(setq a '(3 1 4 1 5 9 6 7)) => (3 1 4 1 5 9 6 7)
(setq a (sort a '<)) => (1 1 3 4 5 6 7 9)
a => (1 1 3 4 5 6 7 9)
</pre>
</div></p>
<p><b>Common Lisp:</b> Common Lisp allows for a ':key' keyword, which
allows a specified function to be run before the ordering takes place, which
XLISP does not support.</p>
<p>See the
<a href="../manual/xlisp-man-017.htm#sort">sort</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
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