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<html><head><title>XLISP macroexpand</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
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<hr>
<h1>macroexpand</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</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(macroexpand <i>form</i>)</dt>
<dd><i>form</i> - a macro form<br>
returns - the macro expansion</dd>
</dl>
<h2>Description</h2>
<p>The 'macroexpand' function takes a 'form' and recursively expands the
macro definitions used in the 'form'. The function returns the expansion. If
the 'form' does not contain a macro, the form is returned unaltered.</p>
<h2>Examples</h2>
<pre class="example">
(defmacro plus (n1 n2) `(+ ,n1 ,n2)) <font color="#008844">; define PLUS macro</font>
(plus 1 2) <font color="#008844">; returns 3</font>
(macroexpand '(plus 3 4)) <font color="#008844">; returns (+ 3 4)</font>
(defmacro pl (p1 p2) `(plus ,p1 ,p2)) <font color="#008844">; define PL macro using PLUS</font>
(pl 3 4) <font color="#008844">; returns 7</font>
(macroexpand '(pl 3 4)) <font color="#008844">; returns (+ 3 4)</font>
(macroexpand-1 '(pl 3 4)) <font color="#008844">; returns (PLUS 3 4)</font>
</pre>
<p><b>Common Lisp:</b> Common Lisp returns 2 values for its result of
'macroexpand', the expanded form and a
<a href="t.htm"> T </a> or
<a href="nil.htm">NIL</a> value that indicates if the form was a
macro. XLISP returns only the expanded form. Common Lisp also supports an
optional argument in 'macroexpand' for the environment of the expansion.
XLISP does not support this optional argument.</p>
<p>See the
<a href="../manual/xlisp-man-012.htm#macroexpand">macroexpand</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
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