GNU bug report logs - #72434
[PATCH] Print list-ending comma/backquote forms specially

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Thuna <thuna.cing <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: [PATCH] Print list-ending comma/backquote forms specially
Date: Sat, 03 Aug 2024 03:31:28 +0200

[Message part 1 (text/plain, inline)]

(This patch follows from 72334, but that patch is not necessary for this
one to work.)

Currently something like the following (unevaluated) form:
  `(foo bar . ,baz)
prints as
  `(foo bar \, baz)
which, while technically accurate, is not helpful.  This comes up quite
often in pcase forms where a pattern like `(,head . ,_) is extremely
common.

This patch fixes that, such that if the tail of a list is a proper list
of two elements whose car is a backquote, comma, or comma-at (so ,foo
,@foo and `foo), and print-quoted is non-nil, the printed text will be
in the first form above.

Better ways to implement this are likely possible; this was simply the
easiest and quickest one.  Feel free to change the patch as needed.

[0001-Print-list-terminating-backquote-and-comma-forms-spe.patch (text/x-patch, attachment)]

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