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<html><head><title>XLISP eval</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>eval</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>xlbfun.c, xleval.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(eval <i>expression</i>)</dt>
<dd><i>expression</i> - an arbitrary expression<br>
returns - the result of evaluating the expression</dd>
</dl>
<h2>Description</h2>
<p>The 'eval' function evaluates the 'expression' and returns the resulting
value.</p>
<h2>Examples</h2>
<pre class="example">
(eval '(+ 2 2)) <font color="#008844">; returns 4</font>
(eval (cons '+ '(2 2 2))) <font color="#008844">; returns 6</font>
(eval (list '+ '2 '3 )) <font color="#008844">; returns 5</font>
(setq a 10) <font color="#008844">; set up A with value 10</font>
(setq b 220) <font color="#008844">; set up B with value 220</font>
(eval (list '+ a b )) <font color="#008844">; returns 230 because</font>
<font color="#008844">; (list '+ a b) => '(+ 10 220)</font>
(eval (list '+ 'a b)) <font color="#008844">; returns 230 because</font>
<font color="#008844">; (list '+ 'a b) => '(+ A 220)</font>
<font color="#008844">; and A has the value 10</font>
</pre>
<p>See the
<a href="../manual/xlisp-man-012.htm#eval">eval</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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