GNU bug report logs - #17623
24.4.50; incorrect example for `apply-partially' in (elisp) `Calling Functions'

Previous Next

Full log

View this message in rfc822 format

From: Eli Zaretskii <eliz <at> gnu.org>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: 17623-done <at> debbugs.gnu.org, stefan <at> marxist.se
Subject: bug#17623: 24.4.50; incorrect example for `apply-partially' in (elisp) `Calling Functions'
Date: Sat, 23 Oct 2021 14:39:02 +0300

> From: Michael Heerdegen <michael_heerdegen <at> web.de>
> Cc: Eli Zaretskii <eliz <at> gnu.org>,  17623-done <at> debbugs.gnu.org
> Date: Sat, 23 Oct 2021 11:44:21 +0200
> 
> I disagree.  The paragraph in the manual explains what the arity of the
> function returned by `apply-partially' would be.
> 
> Directly following is an example suggesting that (apply-partially '+ 1)
> is equivalent to #'1+ - which obviously contradicts that preceding
> paragraph.

In what sense is that a contradiction?  (+ 1 10) is equivalent to (1+ 10),
so we have N = 2 arguments in the original function and M = 1 = N - 1 in
the new one.

> I'm a bit confused that you don't consider this a problem, and also that
> you said there were no concrete suggestions.

That suggestion doesn't make the documentation more clear, IMNSHO,
unless the reader already knows about apply-partially and generally
has a lot of background knowledge about Lisp and Emacs Lisp.  Why are
you saying the suggestion is not being considered, whereas in reality
it was considered (and rejected)?

> There were concrete suggestions for improvements.  One was to simply
> spell out the function that is constructed.  It is only one line, and
> would make the semantics clear.

I cannot disagree more.  That one line doesn't make anything clear, it
just shows the implementation.

> BTW, whenever I posted an example using `apply-partially', Stefan told
> me that it would be more efficient to write out the lambda.  That aspect
> could also be covered: when is worth using?

Concrete proposals for expanding the documentation of apply-partially
(read: patches) will be most welcome, of course.

> Or delete that paragraph, better to say nothing than to confuse readers.

I object to deleting that.  That text certainly helps me, so it cannot
be useless, let alone harmful.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.