<div dir="ltr"><div>Another, better, example:</div><div>Imagine you want to write something like apply,</div><div>but which accepts some optional argument (let's say debug)</div><div><br></div>(define* (my-apply f :rest args (debug #f))<br> (when debug<br> (format *stderr* "passed args: ~A\n" args))<br> (apply f args))<br><br>(my-apply + 1 2 3) ;; debug is 2, not #f<br><br>(my-apply + 1 2 3 :debug #t) ;; args are (1 2 3 :debug #t), debug is 2<br>;; error: + argument 2, :debug, is a symbol but should be a number<br><br>(my-apply :debug #t + 1 2 3 ) ;; error: parameter set twice, debug in (:debug #t + 1 2 3)<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 30 Jul 2021 at 17:21, <<a href="mailto:bil@ccrma.stanford.edu">bil@ccrma.stanford.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I'm not sure I understand the desired functionality.<br>
The arguments after the rest argument should be like<br>
auxiliary arguments in CL (or whatever they are called) --<br>
basically variable declarations? Ah, I looked it up --<br>
&aux in the CL lambda list -- I never used those!<br>
<br>
</blockquote></div>