Re: Is it ok to sort a list of overlays destructively?

[2QdxY4RzWzUUiLuE]

On 2021-07-29 at 18:30:49 +0300,
Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Thu, 29 Jul 2021 08:11:46 -0700
> > From: 2QdxY4RzWzUUiLuE@potatochowder.com
> > 
> > > > I am not sure if such a statement exists in any of the manuals. Should
> > > > it not be stated explicitly somewhere?
> > > 
> > > I don't think it should be, no.  It's pretty much obvious, IMO.
> > 
> > I'm not disagreeing, but why is it obvious?
> 
> Because anything else is a bug, for the same reason that you
> rightfully expect Emacs not to crash when some Lisp program does
> something silly.

That's very thought provoking.  Thank you.

If I believe (and maybe I'm old!) that "Emacs is the extensible,
customizable, self-documenting, real-time display editor," then I
wouldn't be surprised at all if some Lisp program caused Emacs to crash.
After all, those Lisp programs have [a great deal of] access to Emacs'
internals.

I don't realize the expectation you mentioned unless/until I think of
Emacs as platform of some kind, upon which I build a program.  To that
end, https://www.gnu.org/software/emacs/ does now claim that "[a]t its
core is an interpreter for Emacs Lisp, a dialect of the Lisp programming
language with extensions to support text editing."

I'm definitely closer to "it's obvious" than I was earlier.  :-)

My descriptionb of overlays-in (I don't have the C source code handy,
only what appears when I run describe-function in Emacs 27.2) matches
Marcin's and doesn't describe sorting.