Re: Is this a bug in while-let or do I missunderstand it?

[Eli Zaretskii]

> Date: Sat, 09 Nov 2024 18:44:28 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: yuri.v.khan@gmail.com, arthur.miller@live.com, emacs-devel@gnu.org
> 
> > From: "Alfred M. Szmidt" <ams@gnu.org>
> > Cc: arthur.miller@live.com, emacs-devel@gnu.org
> > Date: Sat, 09 Nov 2024 11:33:45 -0500
> > 
> >        (while-let ((run (some-condition)))
> >      (message "running"))
> > 
> >    Do you expect that to evaluate (some-condition) once, then, if it’s
> >    initially true, run forever?
> > 
> > That is how it is described in the manual, so yes (some-condition)
> > should only be done once, and not every iteration.  See (elisp)
> > Conditionals .
> 
> Which could mean that the manual is wrong and needs to be fixed.

The manual might be not explicit enough about this aspect, but it does
say "repeat until a binding in SPEC is ‘nil’", which at least hints
that SPEC is re-evaluated on each iteration.  Because otherwise
repeatedly testing the same result and hoping it will become nil would
be tantamount to the proverbial definition of insanity.