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<html><head><title>XLISP lambda</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>lambda</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>special form (fsubr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xlcont.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(lambda <i>arg-list</i> [<i>body</i>])</dt>
<dd><i>arg-list</i> - a list of the formal arguments to the function of the form:<br>
<dl>
<dd>([<i>arg1</i> ... ]<br>
[<a href="lambda-keyword-optional.htm">&optional</a> <i>oarg1</i> ... ]<br>
[<a href="lambda-keyword-rest.htm">&rest</a> <i>rarg</i>]<br>
[<a href="lambda-keyword-key.htm">&key</a> ... ]<br>
[<a href="lambda-keyword-aux.htm">&aux</a> <i>aux1</i> ... ])</dd>
</dl>
<i>body</i> - a series of LISP forms (expressions) that are executed in order<br>
returns - the function closure</dd>
</dl>
<h2>Description</h2>
<p>The LAMBDA special form returns a function definition [an executable
function] that has no name. All of the 'argN' formal arguments that are
defined are required to appear in a call to the defined function. If there
are any <a href="lambda-keyword-optional.htm">&optional</a> arguments defined,
they will be filled in order. If there is a
<a href="lambda-keyword-rest.htm">&rest</a> argument defined, and all the
required formal arguments and <a href="lambda-keyword-optional.htm">&optional</a>
arguments are filled, any and all further parameters will be passed into the
function via the 'rarg' argument. Note that there can be only one 'rarg'
argument for <a href="lambda-keyword-rest.htm">&rest</a>. If there are
insufficient parameters for any of the
<a href="lambda-keyword-optional.htm">&optional</a> or
<a href="lambda-keyword-rest.htm">&rest</a> arguments, they will contain
<a href="nil.htm">NIL</a>. The
<a href="lambda-keyword-aux.htm">&aux</a> variables are a mechanism for you
to define variables local to the function definition. At the end of the
function execution, these local symbols and their values are are
removed.</p>
<p>Read also the chapter about
<nobr><a href="../manual/xlisp-man-009.htm">lambda lists</a></nobr>
in the <nobr>XLISP 2.0</nobr> manual.</p>
<h2>Examples</h2>
<pre class="example">
(funcall (lambda (a b) (* a b)) 4 8 ) <font color="#008844">; evaluate a lambda function</font>
<font color="#008844">; returns 32</font>
(funcall (lambda '(a b) (+ a b)) 1 2) <font color="#008844">; evaluate another function</font>
<font color="#008844">; returns 3</font>
(funcall (lambda (a b) <font color="#008844">; evaluate a more complex function</font>
(print "a no-name fnc") <font color="#008844">; prints "a no-name fnc"</font>
(* a b)) 3 8) <font color="#008844">; and returns 24</font>
</pre>
<p><b>Note:</b> Using a <a href="setq.htm">setq</a> on a 'lambda'
expression is not the same as a <a href="defun.htm">defun</a>. A
<a href="setq.htm">setq</a> on a 'lambda' will give the
variable the value of the 'lambda' closure. This does not mean that the
variable name can be used as a function.</p>
<p>See the
<a href="../manual/xlisp-man-012.htm#lambda">lambda</a>
special form in the <nobr>XLISP 2.0</nobr> manual.</p>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
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