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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



  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

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