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NNTP-Posting-Date: Sun, 23 Aug 2026 19:47:29 +0000
From: steve g <Sgonedes1977@gmail.com>
Newsgroups: comp.lang.lisp
Subject: Re: Macros (was Re: Resources to learn common lisp?)
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Date: Sun, 23 Aug 2026 15:47:29 -0400
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Xref: csiph.com comp.lang.lisp:61542

antispam@fricas.org (Waldek Hebisch) writes:

> Lawrence D’Oliveiro <ldo@nz.invalid> wrote:
>> 
>>> 3) I would like to so symbolic computation with arbitrary symbols.
>>> For my purpose a symbol is always different from a list. But
>>> polibiuro decided that "NIL" is identical to the empty list. I would
>>> like "NIL" to be a constant symbol which when evaluated gives empty
>>> list.
>> 
>> You want more than one empty-list object? I think that is
>> traditionally treated as a “singleton” (not just in Lisp), which means
>> the answer is “no”.
>
> No, a single empty list object.  I just want symbol NIL to be
> a real symbol distingushable from empty list. Consider



I usually use deconstant or define symbol macro.

(deconst +eof+ '+eof+)

; SLIME 2.27
CL-USER> (defconstant +eof+ '+eof+)

CL-USER> +eof+
+EOF+

CL-USER> (defconstant +eol+ '(nil . nil))
+EOL+
CL-USER> +eol+
(NIL)
CL-USER>