From: Lars Ingebrigtsen <larsi@gnus.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Chunyang Xu <mail@xuchunyang.me>, 24875@debbugs.gnu.org
Subject: bug#24875: 26.0.50; In Dotted Pair Notation, the read function returns CDR if CAR is absent
Date: Tue, 06 Jul 2021 19:15:09 +0200 [thread overview]
Message-ID: <8735srqs82.fsf@gnus.org> (raw)
In-Reply-To: <jwvbl7ftn4q.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Tue, 06 Jul 2021 12:43:58 -0400")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
> It's the "natural" behavior if you start from
>
> (Ea . Ed)
>
> as the notation for cons cells and extend it to
>
> (E1 E2 E3 .. . Ed)
>
> such that
>
> (E1 {foo} . Ed) = (E1 . ({foo} . Ed))
>
> because then you replace `{foo}` with the empty sequence and you get:
>
> (E1 . Ed) = (E1 . ( . Ed))
>
> and hence
>
> Ed = ( . Ed)
>
> It's not used very often, so in theory we could potentially change it,
> but I haven't seen any good alternative interpretation for it, and
> I don't see the benefit of signaling an error.
Ah, I see! Thanks for the explanation -- I now taken a stab at finding
a place in the Lisp manual to explain this (and explaining it slightly
shorter). Feel free to adjust as required.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2021-07-06 17:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-04 13:36 bug#24875: 26.0.50; In Dotted Pair Notation, the read function returns CDR if CAR is absent Chunyang Xu
2016-11-04 16:00 ` Andreas Schwab
2016-11-04 16:00 ` Drew Adams
2021-07-06 15:32 ` Lars Ingebrigtsen
2021-07-06 16:43 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-07-06 17:15 ` Lars Ingebrigtsen [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-05-18 15:04 Drew Adams
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