From: Joost Kremers <joostkremers@fastmail.fm>
To: Eli Zaretskii <eliz@gnu.org>
Cc: arthur.miller@live.com, ams@gnu.org, yuri.v.khan@gmail.com,
emacs-devel@gnu.org
Subject: Re: Is this a bug in while-let or do I missunderstand it?
Date: Tue, 12 Nov 2024 13:45:50 +0100 [thread overview]
Message-ID: <868qto7h8h.fsf@fastmail.fm> (raw)
In-Reply-To: <86ldxoiqzr.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 12 Nov 2024 14:19:36 +0200")
Hi Eli,
Thanks for your comments. I'll take them into account and come up with a
second version.
One question though:
On Tue, Nov 12 2024, Eli Zaretskii wrote:
[...]
> This is too long a description.
I can cut it down, but:
> For starters, I don't see the need to
> justify the existence of the macro (we don't do that for the others).
Currently, before the description of `if-let*`, the manual contains an
explanation of the reason why `if-let*` and friends exist:
```
It can be convenient to bind variables in conjunction with using a
conditional. It's often the case that you compute a value, and then
want to do something with that value if it's non-@code{nil}. The
straightforward way to do that is to just write, for instance:
@example
(let ((result1 (do-computation)))
(when result1
(let ((result2 (do-more result1)))
(when result2
(do-something result2)))))
@end example
Since this is a very common pattern, Emacs provides a number of macros
to make this easier and more readable. The above can be written the
following way instead:
@example
(when-let* ((result1 (do-computation))
(result2 (do-more result1)))
(do-something result2))
@end example
There's a number of variations on this theme, and they're briefly
described below.
```
Since `while-let` is a bit more complex, I thought I'd add a similar
explanation for it. I can try and shorten it, but I gather you think it
should be removed altogether?
> Can we make this shorter and yet clear enough to improve what we have
> there now?
I'll do my best. :-)
--
Joost Kremers
Life has its moments
next prev parent reply other threads:[~2024-11-12 12:45 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-08 16:25 Is this a bug in while-let or do I missunderstand it? arthur miller
2024-11-08 19:23 ` Philip Kaludercic
2024-11-09 3:30 ` Sv: " arthur miller
2024-11-09 9:29 ` Yuri Khan
2024-11-09 13:03 ` Sv: " arthur miller
2024-11-09 13:15 ` Yuri Khan
2024-11-09 13:38 ` Sv: " arthur miller
2024-11-09 13:41 ` Yuri Khan
2024-11-09 13:47 ` Sv: " arthur miller
2024-11-09 14:04 ` Yuri Khan
2024-11-09 14:44 ` Sv: " arthur miller
2024-11-09 16:33 ` Alfred M. Szmidt
2024-11-09 16:44 ` Eli Zaretskii
2024-11-09 16:53 ` Eli Zaretskii
2024-11-09 17:33 ` Andreas Schwab
2024-11-09 18:07 ` [External] : " Drew Adams
2024-11-09 18:18 ` Alfred M. Szmidt
2024-11-09 20:02 ` Jens Schmidt
2024-11-09 20:38 ` Alfred M. Szmidt
2024-11-09 21:18 ` Joost Kremers
2024-11-10 11:44 ` Alfred M. Szmidt
2024-11-10 12:24 ` Better documentation for non-binding clauses of if-let and friends Jens Schmidt
2024-11-10 14:51 ` Sean Whitton
2024-11-10 16:58 ` Jens Schmidt
2024-11-11 10:03 ` Alfred M. Szmidt
2024-11-11 8:20 ` Alfred M. Szmidt
2024-11-09 19:32 ` Sv: [External] : Re: Is this a bug in while-let or do I missunderstand it? arthur miller
2024-11-09 22:36 ` Drew Adams
2024-11-09 22:53 ` Drew Adams
2024-11-14 21:50 ` John ff
2024-11-09 20:29 ` Sv: " arthur miller
2024-11-10 6:22 ` Eli Zaretskii
2024-11-10 10:40 ` Joost Kremers
2024-11-10 12:10 ` Alfred M. Szmidt
2024-11-10 19:49 ` Sv: " arthur miller
2024-11-10 18:18 ` arthur miller
2024-11-11 5:13 ` Yuri Khan
2024-11-11 8:49 ` Sv: " arthur miller
2024-11-11 12:23 ` tomas
2024-11-11 22:41 ` Joost Kremers
2024-11-12 12:19 ` Eli Zaretskii
2024-11-12 12:45 ` Joost Kremers [this message]
2024-11-12 14:34 ` Eli Zaretskii
2024-11-12 15:32 ` Joost Kremers
2024-11-12 23:45 ` Joost Kremers
2024-11-13 9:45 ` Sean Whitton
2024-11-13 9:56 ` Sean Whitton
2024-11-13 11:00 ` Joost Kremers
2024-11-13 12:17 ` Sean Whitton
2024-11-14 7:55 ` Eli Zaretskii
2024-11-14 8:21 ` Joost Kremers
2024-11-14 21:51 ` John ff
2024-11-14 21:52 ` John ff
2024-11-09 21:47 ` Sv: " Joost Kremers
2024-11-09 22:07 ` Sv: " arthur miller
2024-11-10 6:07 ` Andreas Schwab
-- strict thread matches above, loose matches on Subject: below --
2024-11-12 3:36 arthur miller
2024-11-12 8:30 ` Joost Kremers
2024-11-12 17:55 ` Alfred M. Szmidt
2024-11-12 3:41 arthur miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=868qto7h8h.fsf@fastmail.fm \
--to=joostkremers@fastmail.fm \
--cc=ams@gnu.org \
--cc=arthur.miller@live.com \
--cc=eliz@gnu.org \
--cc=emacs-devel@gnu.org \
--cc=yuri.v.khan@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).