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<html><head>
<title>cl:values</title>
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<a href="../../start.htm">Nyquist / XLISP 2.0</a> -
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<hr>
<h1>cl:values</h1>
<hr>
<p>The <nobr>cl:<b>values</b></nobr> function evaluates all given Lisp
expressions and returns the results as multiple values:</p>
<p><div class="box">
<dl>
<dt>(cl:<b>values</b> [<i>expr1</i> ...])</dt>
<dd><i>exprN</i> - an arbitrary Lisp expression<br>
returns - the results of evaluating the expressions, as multiple values</dd>
</dl>
</div></p>
<pre class="example">
(defun <font color="#0000CC">cl:values</font> (&rest exprs)
(setq <font color="#AA5500">*rslt*</font> exprs
<font color="#AA5500">cl:*multiple-values*</font> t)
(first exprs))
</pre>
<p>The primary return value <nobr>[the result</nobr> from evaluating the
first expression] is returned by the <nobr>cl:<b>values</b></nobr> function
and a list with the results of evaluating all expressions is assigned to the
Nyquist <a href="../../reference/global-rslt.htm">*rslt*</a> variable.
<nobr>If no</nobr> expressions are given,
<a href="..././reference/nil.htm">NIL</a> is returned and the
<a href="../../reference/global-rslt.htm">*rslt*</a> variable is set
<nobr>to <a href="../../reference/nil.htm">NIL</a></nobr>.</p>
<p><nobr>The
<a href="global-multiple-values.htm">cl:*multiple-values*</a></nobr>
variable is set
<nobr>to <a href="../../reference/t.htm"> T </a></nobr>
to indicate that multiple values are returned.</p>
<p>Examples:</p>
<pre class="example">
(cl:values 1 2 3) => 1 <font color="#008844">; primary value</font>
*rslt* => (1 2 3) <font color="#008844">; all values</font>
(cl:values 'a 'b) => A <font color="#008844">; primary value</font>
*rslt* => (A B) <font color="#008844">; all values</font>
> (cl:multiple-value-bind (a b c)
(cl:values 1 2 3)
(list a b c))
(1 2 3)
</pre>
<p>See
<nobr><a href="multiple-value-bind.htm">cl:multiple-value-bind</a></nobr>,
<a href="../../reference/list.htm">list</a>,
<a href="../../reference/global-rslt.htm">*rslt*</a>.</p>
<p><div class="box">
<p><b>Known Limitations</b></p>
<p><b>1.</b> In Nyquist/XLISP, <nobr>cl:<b>values</b></nobr> cannot be
used as argument to <a href="../../reference/setf.htm">setf</a>. <nobr>But
this</nobr> is not a real problem, because the values are stored as a
simple list in the <a href="../../reference/global-rslt.htm">*rslt*</a>
variable, where they can be manipulated with any arbitrary Lisp
functions, not only <nobr>with
<a href="../../reference/setf.htm">setf</a></nobr>.</p>
<p><b>2.</b> In <nobr>Common Lisp</nobr> there exists the option to return
<nobr>'no value</nobr>' by calling the 'values' function with no arguments.
<nobr>In Nyquist/XLISP</nobr> there is no <nobr>built-in</nobr> way to
return '<nobr>no value</nobr>' from a function. <nobr>The symbol</nobr>
<a href="../../reference/global-unbound.htm">*unbound*</a> cannot be used for
this because in <nobr>Common Lisp</nobr>, if '<nobr>no value</nobr>' is
assigned to a symbol as variable value, the new value will be
<a href="../../reference/nil.htm">NIL</a> and not
<a href="../../reference/global-unbound.htm">*unbound*</a>.</p>
<p>In Nyquist/XLISP, the cl:<b>values</b> function, if called with no
arguments, always returns <a href="../../reference/nil.htm">NIL</a>, and the
<a href="../../reference/global-rslt.htm">*rslt*</a> variable will be
set <nobr>to <a href="../../reference/nil.htm">NIL</a>, too:</nobr></p>
<pre class="example">
(cl:values) => NIL <font color="#008844">; primary value</font>
*rslt* => NIL <font color="#008844">; all values</font>
(cl:values nil) => NIL <font color="#008844">; primary value</font>
*rslt* => (NIL) <font color="#008844">; all values</font>
</pre>
<p>Maybe this observation helps to write a '<nobr>no values</nobr>' test if
anybody really <nobr>needs it</nobr>.</p>
</div></p>
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