Re: Predicate for true lists

[Eli Zaretskii]

> Date: Fri, 6 Jul 2018 10:16:11 -0700 (PDT)
> From: Drew Adams <address@hidden>
> Cc: address@hidden, address@hidden
> 
> > Do we really want this usage of the function as a predicate?  I find
> > this slightly unnatural, and also not future-proof enough, because you
> > rely on the checks 'length' does internally.  If the internals of
> > 'length' change one day, this predicate usage will collapse like a
> > house of cards.  Would it make more sense to have a separate
> > predicate?
> 
> IIRC, the main motivation for adding this function was
> to provide a predicate for testing properness.

Then I'd prefer calling the function proper-list-p (and returning the
list length when it's a proper list) than the other way around.