GNU bug report logs - #61281
“`(a \, b)” equals to “`(a . ,b)”

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From: Andreas Schwab <schwab <at> suse.de>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: Xie Shynur <one.last.kiss <at> outlook.com>, "61281 <at> debbugs.gnu.org" <61281 <at> debbugs.gnu.org>, Drew Adams <drew.adams <at> oracle.com>
Subject: bug#61281: “`(a \, b)” equals to “`(a . , b)”
Date: Mon, 06 Feb 2023 10:40:36 +0100

On Feb 06 2023, Michael Heerdegen wrote:

> S-exps are defined recursively.  ",X" is read syntax of a valid s-exp,
> and I don't think we want to make the reader raise an error for it.

FWIW, clisp generates an error if the comma occurs outside of backquote.
If you quote the comma, it is treated as an ordinary symbol character.

$ clisp -q -x ',X'
*** - READ: comma is illegal outside of backquote
$ clisp -q -x '\,X'
*** - SYSTEM::READ-EVAL-PRINT: variable |,X| has no value

$ clisp -q -x '`\,X'
|,X|

-- 
Andreas Schwab, SUSE Labs, schwab <at> suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
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