GNU bug report logs - #72888
Confusing descriptive text

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

From: 麻枝忠 <maedaqu <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Confusing descriptive text
Date: Fri, 30 Aug 2024 14:58:47 +0800

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

Equality Predicates (GNU Emacs Lisp Reference Manual)
<https://www.gnu.org/software/emacs/manual/html_node/elisp/Equality-Predicates.html>

In the descriptive text of function "equal":

"The equal function recursively compares the contents of objects if they
are integers, strings, markers, vectors, bool-vectors, byte-code function
objects, char-tables, records, or font objects."

Shouldn't "integers" here be "conses" or "lists"?

[Message part 2 (text/html, inline)]

Message #10 received at 72888-done <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: 麻枝忠 <maedaqu <at> gmail.com>
Cc: 72888-done <at> debbugs.gnu.org
Subject: Re: bug#72888: Confusing descriptive text
Date: Fri, 30 Aug 2024 13:59:34 +0300

> From: 麻枝忠 <maedaqu <at> gmail.com>
> Date: Fri, 30 Aug 2024 14:58:47 +0800
> 
> Equality Predicates (GNU Emacs Lisp Reference Manual)
> 
> In the descriptive text of function "equal":
> 
> "The equal function recursively compares the contents of objects if they are integers, strings, markers, vectors,
> bool-vectors, byte-code function objects, char-tables, records, or font objects."
> 
> Shouldn't "integers" here be "conses" or "lists"?

No (an integer could be a fixnum or a bignum), but lists and conses
should be in that list.  I've now added that on the emacs-30 release
branch, and I'm therefore closing this bug.  Thanks for pointing out
the omission.

Message #13 received at 72888 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 72888 <at> debbugs.gnu.org, 麻枝忠 <maedaqu <at> gmail.com>
Subject: bug#72888: Confusing descriptive text
Date: Sat, 31 Aug 2024 14:37:26 +0200

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

Thank you for making this text better. It can be made even more accurate: neither integers nor strings or bool-vectors are actually compared recursively in a useful sense so we shouldn't claim that they are, and nowadays both byte-compiled and interpreted closures are compiled but we should note the usual intensionality problems when comparing functions.

Here is a proposed amendment.

[equal-doc.diff (application/octet-stream, attachment)]

Message #16 received at 72888 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Cc: 72888 <at> debbugs.gnu.org, maedaqu <at> gmail.com
Subject: Re: bug#72888: Confusing descriptive text
Date: Sat, 31 Aug 2024 15:58:32 +0300

> From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
> Date: Sat, 31 Aug 2024 14:37:26 +0200
> Cc: 麻枝忠 <maedaqu <at> gmail.com>,
>  72888 <at> debbugs.gnu.org
> 
> Thank you for making this text better. It can be made even more accurate: neither integers nor strings or bool-vectors are actually compared recursively in a useful sense so we shouldn't claim that they are, and nowadays both byte-compiled and interpreted closures are compiled but we should note the usual intensionality problems when comparing functions.
> 
> Here is a proposed amendment.

Doesn't that lose useful information?  It only tells what is compared
recursively, but doesn't tell about comparing strings or integers or
bool-vectors by themselves, which is IMO important.

IOW, given your proposed text, how do we explain that

  (equal "foo" (substring "foobar" nil -3)) => t

Message #19 received at 72888 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 72888 <at> debbugs.gnu.org, maedaqu <at> gmail.com
Subject: Re: bug#72888: Confusing descriptive text
Date: Sat, 31 Aug 2024 16:37:56 +0200

31 aug. 2024 kl. 14.58 skrev Eli Zaretskii <eliz <at> gnu.org>:

> Doesn't that lose useful information?  It only tells what is compared
> recursively, but doesn't tell about comparing strings or integers or
> bool-vectors by themselves, which is IMO important.

That's a fair point. What about something like:

The @code{equal} function compares numbers, strings and bool-vectors by
value.  Lists, cons cells, vectors, records, markers, char-tables,
font objects, and function objects (closures)@footnote{However, equality
of distinct function objects cannot be guaranteed in general.} are
compared recursively by using @code{equal} on their constituent parts.

Message #22 received at 72888 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Mattias Engdegård <mattias.engdegard <at> gmail.com>
Cc: 72888 <at> debbugs.gnu.org, maedaqu <at> gmail.com
Subject: Re: bug#72888: Confusing descriptive text
Date: Sat, 31 Aug 2024 19:07:34 +0300

> From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
> Date: Sat, 31 Aug 2024 16:37:56 +0200
> Cc: maedaqu <at> gmail.com,
>  72888 <at> debbugs.gnu.org
> 
> 31 aug. 2024 kl. 14.58 skrev Eli Zaretskii <eliz <at> gnu.org>:
> 
> > Doesn't that lose useful information?  It only tells what is compared
> > recursively, but doesn't tell about comparing strings or integers or
> > bool-vectors by themselves, which is IMO important.
> 
> That's a fair point. What about something like:
> 
> The @code{equal} function compares numbers, strings and bool-vectors by
> value.  Lists, cons cells, vectors, records, markers, char-tables,
> font objects, and function objects (closures)@footnote{However, equality
> of distinct function objects cannot be guaranteed in general.} are
> compared recursively by using @code{equal} on their constituent parts.

SGTM, thanks.

Message #25 received at 72888 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattias.engdegard <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 72888 <at> debbugs.gnu.org, maedaqu <at> gmail.com
Subject: Re: bug#72888: Confusing descriptive text
Date: Sat, 31 Aug 2024 18:47:27 +0200

31 aug. 2024 kl. 18.07 skrev Eli Zaretskii <eliz <at> gnu.org>:

> SGTM, thanks.

Thank you, push with minor tweak to emacs-30.

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