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Re: [External] : Re: Shrinking the C core

From: João Távora
Subject: Re: [External] : Re: Shrinking the C core
Date: Mon, 11 Sep 2023 16:10:26 +0100

On Mon, Sep 11, 2023 at 1:40 AM Richard Stallman <rms@gnu.org> wrote:

> Keyword arguments are fine for an unusual, heavyweight operation such
> as creating a frame.  The sort of function whose doc you need to look
> up again each time you use it.  When something is as cumbersome as
> that, the question of how to pass the arguments is a pile of minor
> details that you'll see when you look it up.

It's possible that in 1984 there weren't any good at-point-documentation
systems that immediately show the available keyword arguments of a given
call being typed.  I was very young at the time, so I can't attest to it.

But nowadays such systems exist, including built-in, in Emacs.

But even in the absence of those conveniences, each family of functions
in CL, (say, the sequence manipulating functions) take standard sets
of keyword arguments (like :START, :END, :FROM-END, :KEY, :TEST).

This makes them very easy to remember and makes using e.g. CL's SORT
much more practical than Emacs Lisp 'sort'.

> But it's a pain in the neck to make simple everyday functions such as
> `append' and `length' that cumbersome just for the sake of following a
> general system.

APPEND and LENGTH in Common Lisp do not take keyword arguments,
(nor have they ever?) so I believe your argument is weakened by
criticizing a suggestion that no-one is offering.

Let's look at a traditional Elisp macro define-minor-mode.

According to the CVS history, you created this function in 1997, with
three positional optional arguments.  Then more and more arguments
came along.  Possibly due to the realization by Emacs developers
around 2000, already more than 20 years ago,  that positional arguments
are maintenance hazards, the macro now accepts keyword arguments
(and the positional arguments are actively discouraged).

Unfortunately, because cl-lib.el wasn't used for this particular change,
the aforementioned at-point documentation facilities aren't available,
which, to some of us, would appear just another manifestation of
Greenspun's 10th rule (which I assume everyone in this niche topic
is familar with).

Many other functions with a large amount of optional arguments
(completing-read comes to mind) would be much, much easier
to use with keyword arguments.  Without them, we find ourselves
wondering about how many nils to sprinkle before the argument
we want to pass.


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