Re: Check whether an object is an alist

[tomas@tuxteam.de]

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On Tue, Sep 17, 2024 at 11:16:24AM +0000, Heime wrote:
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> Sent with Proton Mail secure email.
> 
> On Tuesday, September 17th, 2024 at 9:46 PM, tomas@tuxteam.de <tomas@tuxteam.de> wrote:
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> > On Tue, Sep 17, 2024 at 11:38:46AM +0200, Manuel Giraud via Users list for the GNU Emacs text editor wrote:
> > 
> > > Heime heimeborgia@protonmail.com writes:
> > > 
> > > > Sent with Proton Mail secure email.
> > > > 
> > > > On Monday, September 16th, 2024 at 10:29 PM, Heime heimeborgia@protonmail.com wrote:
> > > > 
> > > > > Is there a function that checks whether an object is an alist.
> > > > > Have only found listp.
> > > > 
> > > > Because I may have to come up with a solution, I have made this one.
> > > > Am I missing anything ?
> > > > 
> > > > (defun torium-alist-p (obj)
> > > > "Return t if object OBJ is an association list (alist)."
> > > > (and (listp obj)
> > > > (not (null obj))
> > > > (every (lambda (x)
> > > > (and (consp x)
> > > > (not (null x))))
> > > > obj)))
> > > 
> > > Looks good to me. I think it should `cl-every' instead of` every' and
> > > also, maybe, nil is a valid empty alist.
> > 
> > 
> > Unless you'd like to have nil as a possible key (alists allow that,
> > why not?):
> > 
> > (setq al '((nil . "I am not") (t . "I am")))
> > (alist-get nil al)
> > => "I am not"

Oh, wait. I just see you were checking the pair to be not
null. Then it's easier: your above code seems right, just
the (not (null x)) is superfluous, since (consp x) makes
sure it is so.

Cheers
-- 
t

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