GNU bug report logs - #76476
Make cl-first, cl-second, ..., cl-tenth part of Emacs Lisp

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

From: Stefan Kangas <stefankangas <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Make cl-first, cl-second, ..., cl-tenth part of Emacs Lisp
Date: Fri, 21 Feb 2025 18:40:46 +0000

Severity: wishlist

I propose making the following functions from cl-lib.el a part of
Emacs Lisp proper (i.e. defined in subr.el):

    first
    second
    third
    fourth
    fifth
    sixth
    seventh
    eight
    ninth
    tenth
    rest

This would allow converting code such as:

    (mapcar (lambda (thing) (car (cdr (cdr (cdr thing))))) ...)
    (mapcar (lambda (thing) (cadddr thing)) ...)
    (mapcar (lambda (thing) (nth 3 thing)) ...)

to the IMHO, more direct and readable:

    (mapcar #'fourth ...)

I'm adding `rest' to the list as well, as the natural corollary to
`first'.

Which would be used is obviously situational, and should be left to
whoever is touching that code.  There is no general need to "upgrade"
old code to prefer these new functions.

Thoughts?

Message #8 received at 76476 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: Stefan Kangas <stefankangas <at> gmail.com>, "76476 <at> debbugs.gnu.org"
 <76476 <at> debbugs.gnu.org>
Cc: "eliz <at> gnu.org" <eliz <at> gnu.org>, "acorallo <at> gnu.org" <acorallo <at> gnu.org>,
 "monnier <at> iro.umontreal.ca" <monnier <at> iro.umontreal.ca>
Subject: RE: [External] : bug#76476: Make cl-first, cl-second, ..., cl-tenth
 part of Emacs Lisp
Date: Fri, 21 Feb 2025 20:39:21 +0000

> Severity: wishlist
> 
> I propose making the following functions from cl-lib.el a part of
> Emacs Lisp proper (i.e. defined in subr.el):
> 
>     first
>     second
>     third
>     fourth
>     fifth
>     sixth
>     seventh
>     eight
>     ninth
>     tenth
>     rest
> 
> This would allow converting code such as:
> 
>     (mapcar (lambda (thing) (car (cdr (cdr (cdr thing))))) ...)
>     (mapcar (lambda (thing) (cadddr thing)) ...)
>     (mapcar (lambda (thing) (nth 3 thing)) ...)

Aka (mapcar #'cadddr ...)  ;-)

> to the IMHO, more direct and readable:
> 
>     (mapcar #'fourth ...)
> 
> I'm adding `rest' to the list as well, as the natural corollary to
> `first'.
> 
> Which would be used is obviously situational, and should be left to
> whoever is touching that code.  There is no general need to "upgrade"
> old code to prefer these new functions.
> 
> Thoughts?

Since you asked...

There are about 8 zillion things in cl-* that it would
be more useful to add to Elisp (without prefix `cl-')
than those functions.

That said, it wouldn't hurt to add those functions, but
why not do something more useful while you're at it?

E.g., something like cl-case (sans cl-) should have been
added to Elisp eons ago.  (And in fact if you loaded
cl.el you got it as `case', not `cl-case', originally.)

Better to look for more useful parts of cl-lib...

Message #11 received at 76476 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Stefan Kangas <stefankangas <at> gmail.com>
Cc: 76476 <at> debbugs.gnu.org, eliz <at> gnu.org, acorallo <at> gnu.org
Subject: Re: bug#76476: Make cl-first, cl-second, ..., cl-tenth part of
 Emacs Lisp
Date: Fri, 21 Feb 2025 17:30:50 -0500

> I propose making the following functions from cl-lib.el a part of
> Emacs Lisp proper (i.e. defined in subr.el):
>
>     first
>     second
>     third
>     fourth
>     fifth
>     sixth
>     seventh
>     eight
>     ninth
>     tenth
>     rest

FWIW, I hate those even more than the `cadar` thingies.  🙂

For direct calls, `nth` is always a better choice (except for `first`
and `rest`, of course, where `car/cdr` would be the replacement), so the
only use case is when you pass them as arg somewhere, but that doesn't
seem to be very frequent.
[ And for those rare cases, an approach like llama's (##nth N %) is
  a more general solution to the problem.  ]


        Stefan

Message #14 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Howard Melman <hmelman <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#76476: Make cl-first, cl-second, ...,
 cl-tenth part of Emacs Lisp
Date: Sun, 23 Feb 2025 12:57:31 -0500

Stefan Monnier via "Bug reports for GNU Emacs, the Swiss
army knife of text editors" <bug-gnu-emacs <at> gnu.org> writes:

>> I propose making the following functions from cl-lib.el a part of
>> Emacs Lisp proper (i.e. defined in subr.el):
>>
>>     first
>>     second
>>     third
>>     fourth
>>     fifth
>>     sixth
>>     seventh
>>     eight
>>     ninth
>>     tenth
>>     rest
>
> FWIW, I hate those even more than the `cadar` thingies.  🙂
>
> For direct calls, `nth` is always a better choice (except for `first`
> and `rest`, of course, where `car/cdr` would be the replacement), so the
> only use case is when you pass them as arg somewhere, but that doesn't
> seem to be very frequent.

I like these for the case where something returns a sequence
and the documentation (particularly docstrings) refers to
"the third element is...". In this situation, nth being
zero-indexed makes off-by-one errors more likely.

-- 

Howard

Message #17 received at 76476 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 76476 <at> debbugs.gnu.org, eliz <at> gnu.org, acorallo <at> gnu.org,
 stefankangas <at> gmail.com
Subject: Re: bug#76476: Make cl-first, cl-second, ...,
 cl-tenth part of Emacs Lisp
Date: Mon, 24 Feb 2025 07:10:33 -0500

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > >     first
  > >     second
  > >     third
  > >     fourth
  > >     fifth
  > >     sixth
  > >     seventh
  > >     eight
  > >     ninth
  > >     tenth
  > >     rest

  > FWIW, I hate those even more than the `cadar` thingies.  🙂

I agree -- most of these are no improvement.  They don't make programs
simpler.

We no longer have a need to strain to keep the number of function
names in GNU Emacs as small as possible.  But that doesn't mean
we should add every function that could be meaningful.
Some meaningful functions are not worth the work of documenting them.


-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Message #20 received at 76476 <at> debbugs.gnu.org (full text, mbox):

From: "Alfred M. Szmidt" <ams <at> gnu.org>
To: Drew Adams <drew.adams <at> oracle.com>
Cc: 76476 <at> debbugs.gnu.org, eliz <at> gnu.org, acorallo <at> gnu.org,
 stefankangas <at> gmail.com, monnier <at> iro.umontreal.ca
Subject: Re: bug#76476: Make cl-first, cl-second, ...,
 cl-tenth part of Emacs Lisp
Date: Mon, 24 Feb 2025 11:02:48 -0500

   There are about 8 zillion things in cl-* that it would
   be more useful to add to Elisp (without prefix `cl-')
   than those functions.

I am also curious about why these things are being added?  What for?

They (as several people have mentioned) do not make code easier to
read, and we already had a quite debacle about this CLification.

   That said, it wouldn't hurt to add those functions, but
   why not do something more useful while you're at it?

   E.g., something like cl-case (sans cl-) should have been
   added to Elisp eons ago.  (And in fact if you loaded
   cl.el you got it as `case', not `cl-case', originally.)

INCF.

   Better to look for more useful parts of cl-lib...

Message #25 received at 76476-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefankangas <at> gmail.com>
To: rms <at> gnu.org, Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: acorallo <at> gnu.org, eliz <at> gnu.org, 76476-done <at> debbugs.gnu.org
Subject: Re: bug#76476: Make cl-first, cl-second, ...,
 cl-tenth part of Emacs Lisp
Date: Mon, 24 Feb 2025 16:33:41 +0000

Richard Stallman <rms <at> gnu.org> writes:

>   > >     first
>   > >     second
>   > >     third
>   > >     fourth
>   > >     fifth
>   > >     sixth
>   > >     seventh
>   > >     eight
>   > >     ninth
>   > >     tenth
>   > >     rest
>
>   > FWIW, I hate those even more than the `cadar` thingies.  🙂
>
> I agree -- most of these are no improvement.  They don't make programs
> simpler.
>
> We no longer have a need to strain to keep the number of function
> names in GNU Emacs as small as possible.  But that doesn't mean
> we should add every function that could be meaningful.
> Some meaningful functions are not worth the work of documenting them.

Thanks.  It appears that this change isn't gaining much support.

I'm therefore closing this bug report now.

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