From: Marcin Borkowski <mbork@mbork.pl>
To: Help Gnu Emacs mailing list <help-gnu-emacs@gnu.org>
Subject: How to mapcar or across a list?
Date: Wed, 15 Jul 2015 22:14:20 +0200 [thread overview]
Message-ID: <87io9lmb4z.fsf@mbork.pl> (raw)
Hi there,
so here's my problem: I have a list of Boolean values, and I want to
`mapcar' an `or' across it (IOW, I want to test whether at least one of
them is true). Of course, (apply #'or my-list) does not work. Of
course, I can (cl-reduce (lambda (x y) (or x y)) my-list) -- but is
there a better method?
BTW, my-list doesn't really exist: it is a result of `mapcar'ing
a function taking some value and yielding a Boolean value, so bonus
points if the method does not process the whole list.
(Note: I just noticed that my-list is in fact sorted so that all true
values (if any) will occur at the beginning anyway, so I can just test
the first one. This means that my problem is purely academic, though
still interesting, I guess.)
Best,
--
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University
next reply other threads:[~2015-07-15 20:14 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 20:14 Marcin Borkowski [this message]
2015-07-15 20:42 ` How to mapcar or across a list? Rasmus
2015-07-15 20:55 ` Marcin Borkowski
2015-07-15 22:21 ` Emanuel Berg
2015-07-15 22:21 ` John Mastro
[not found] ` <mailman.6977.1436998965.904.help-gnu-emacs@gnu.org>
2015-07-15 22:28 ` Pascal J. Bourguignon
2015-07-15 22:36 ` Emanuel Berg
2015-07-15 22:57 ` never use `eval' (was: Re: How to mapcar or across a list?) Emanuel Berg
2015-07-15 23:27 ` John Mastro
2015-07-15 23:57 ` Emanuel Berg
2015-07-16 0:18 ` John Mastro
[not found] ` <mailman.6984.1437004760.904.help-gnu-emacs@gnu.org>
2015-07-16 0:04 ` Barry Margolin
[not found] ` <mailman.6982.1437001117.904.help-gnu-emacs@gnu.org>
2015-07-16 0:01 ` Barry Margolin
2015-07-16 1:13 ` Emanuel Berg
2015-07-17 0:55 ` Emanuel Berg
[not found] ` <mailman.7027.1437094623.904.help-gnu-emacs@gnu.org>
2015-07-17 1:39 ` never use `eval' Pascal J. Bourguignon
2015-07-17 2:16 ` Emanuel Berg
2015-07-17 8:36 ` Barry Margolin
2015-07-17 8:55 ` Pascal J. Bourguignon
2015-07-16 0:22 ` Pascal J. Bourguignon
2015-07-16 1:11 ` Emanuel Berg
[not found] <mailman.6968.1436991281.904.help-gnu-emacs@gnu.org>
2015-07-15 20:45 ` How to mapcar or across a list? Pascal J. Bourguignon
2015-07-15 21:02 ` Marcin Borkowski
2015-07-15 23:56 ` Barry Margolin
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