[clisp-list] Re: &optional and &key lambda list keywords

[Sam S. <sd...@gn...>]

> * In message <NHE...@sy...>
> * On the subject of "&optional and &key lambda list keywords"
> * Sent on Sun, 2 Jun 2002 10:05:36 -0700
> * Honorable "Dave Richards" <da...@sy...> writes:
>
> I thought I understood these two keywords, but it appears I do not.
> Is it true that keyword parameters assume the existence of optional
> arguments?
yes.

> (defun test (a &optional b &key c)
>   (list a b c))
> [5]> (test 1 :c 3)
> 
> *** - EVAL/APPLY: keyword arguments for TEST should occur pairwise
> 1. Break [6]>

a==1
b==:c
3 is supposed to be :c
the c argument is missing.

<http://www.lisp.org/HyperSpec/Body/sec_3-4-1-6.html>
<http://www-jcsu.jesus.cam.ac.uk/~csr21/lispfaq.html#AEN257>

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