From: Drew Adams <drew.adams@oracle.com>
To: Heime <heimeborgia@protonmail.com>,
Joost Kremers <joostkremers@fastmail.fm>
Cc: "help-gnu-emacs@gnu.org" <help-gnu-emacs@gnu.org>
Subject: RE: [External] : Re: Testing whether a list contains at least one non-nil element
Date: Tue, 25 Oct 2022 20:15:25 +0000 [thread overview]
Message-ID: <CO6PR10MB547349E6CE71ACCC35A89ED2F3319@CO6PR10MB5473.namprd10.prod.outlook.com> (raw)
In-Reply-To: <ODC_sHi308FT03Ga8vMOJsu-tkYjFLy80nZMhFcBlInyM5y_12AevH9mXQgTmKlPMSKy8MI1iCbTEeLqJCs0CKdANAJCDCApM9BQ3ZrNQhY=@protonmail.com>
> > > I would like to test whether a list contains at least one
> > > non-nil element? If I do that, then I would be able to
> > > continue a loop where a non-nil element would mean
> > > that a match was found.
> >
> > (seq-some (lambda (e) (not (null e))) mylist)
> >
> > or shorter:
> >
> > (not (seq-every-p #'null mylist))
>
> How does your implementation (not (seq-every-p #'null mylist)) compared to
>
> (elt (delq nil mylist) 0)
`delq' is a "destructive" operation. It can, and
generally does, modify list structure. Is that what
you intend? That's something other than just doing
a "test whether a list contains at least one non-nil
element."
Be very careful and know what you're doing, and why,
if you start writing code that modifies list structure.
next prev parent reply other threads:[~2022-10-25 20:15 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 10:16 Testing whether a list contains at least one non-nil element Heime
2022-10-25 10:46 ` Jean Louis
2022-10-25 10:47 ` Jean Louis
2022-10-25 10:50 ` Jean Louis
2022-10-25 12:12 ` Emanuel Berg
2022-10-26 18:56 ` Jean Louis
2022-10-27 3:54 ` [External] : " Drew Adams
2022-10-27 4:53 ` Jean Louis
2022-10-27 5:30 ` Emanuel Berg
2022-10-27 15:54 ` Drew Adams
2022-10-27 17:47 ` Elisp and CL (was: Re: [External] : Re: Testing whether a list contains at least one non-nil element) Emanuel Berg
2022-10-27 20:38 ` [External] : Re: Testing whether a list contains at least one non-nil element Jean Louis
2022-10-28 0:22 ` Emanuel Berg
2022-10-28 4:48 ` tomas
2022-10-28 5:19 ` Jean Louis
2022-10-28 6:20 ` Michael Heerdegen
2022-10-28 13:09 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-10-29 6:10 ` Michael Heerdegen
2022-10-29 15:25 ` Stefan Monnier via Users list for the GNU Emacs text editor
2022-10-30 12:49 ` Emanuel Berg
2022-10-29 6:38 ` tomas
2022-10-30 12:48 ` Emanuel Berg
2022-10-29 9:20 ` Emanuel Berg
2022-10-29 9:19 ` Emanuel Berg
2022-10-27 4:01 ` Emanuel Berg
2022-10-25 12:05 ` Michael Heerdegen
2022-10-25 12:15 ` Emanuel Berg
2022-10-25 15:59 ` [External] : " Drew Adams
2022-10-25 17:44 ` Emanuel Berg
2022-10-26 15:39 ` Drew Adams
2022-10-26 17:43 ` Emanuel Berg
2022-10-25 17:25 ` Joost Kremers
2022-10-25 17:51 ` Emanuel Berg
2022-10-25 19:44 ` Heime
2022-10-25 20:08 ` Joost Kremers
2022-10-25 20:15 ` Drew Adams [this message]
2022-10-25 20:19 ` [External] : " Joost Kremers
2022-10-26 3:00 ` Stefan Monnier via Users list for the GNU Emacs text editor
-- strict thread matches above, loose matches on Subject: below --
2022-10-28 5:07 Drew Adams
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