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From: Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: `apply-partially` and hash tables
Date: Sun, 20 Oct 2024 16:29:10 -0400	[thread overview]
Message-ID: <jwvplnu5xjt.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: m1ed4a6126.fsf@constantly.at

Rudolf Schlatte [2024-10-20 21:12:33] wrote:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> My question is the same, though: can it be relied upon?
>>
>> It's fundamental to the notion of what is a *value* (as in "call by
>> value"), so yes, very much so.
>
> The usual caveat for lists applies: prepending values to the front or
> otherwise mutating the list will not work as expected in general, since
> what you're holding is just a cons cell.  (This is an instance of the
> "delete bug" where you have to write `(setq x (delete 'foo x))' instead
> of just `(delete 'foo x)'.)

AFAICT this behavior is a direct result of that same fundamental
difference between a value and the thing it refers to, so not a caveat
at all.


        Stefan




      reply	other threads:[~2024-10-20 20:29 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-20  9:43 `apply-partially` and hash tables Joost Kremers
2024-10-20  9:54 ` tomas
2024-10-20 14:46 ` Stefan Monnier via Users list for the GNU Emacs text editor
2024-10-20 15:19   ` Joost Kremers
2024-10-20 17:04     ` Stefan Monnier
2024-10-20 19:12       ` Rudolf Schlatte
2024-10-20 20:29         ` Stefan Monnier via Users list for the GNU Emacs text editor [this message]

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