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<html><head><title>XLISP nil</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> |
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<a href="../examples/examples.htm">Examples</a> |
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<hr>
<h1>nil</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>system constant</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xlsym.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt> nil</dt>
</dl>
<h2>Description</h2>
<p>The 'nil' constant represents the empty list or the false value, as
oppossed to the true value [the symbol
<a href="t.htm"> T </a>]. 'nil' can be written as
the three character symbol 'nil' or as the empty list ().</p>
<h2>Examples</h2>
<pre class="example">
(setq myvar nil) <font color="#008844">; set MYVAR to False</font>
(setq myvar 'nil) <font color="#008844">; NIL and 'NIL evaluate to NIL</font>
(setq myvar ()) <font color="#008844">; () is the empty list = NIL</font>
(setq myvar '()) <font color="#008844">; () and '() evaluate to NIL</font>
(if nil (print "this won't print") <font color="#008844">; if/then/else</font>
(print "this will print"))
</pre>
<p><b>Note:</b> You can not change the value of NIL.</p>
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