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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



             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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