From: Drew Adams <drew.adams@oracle.com>
To: Stefan Huchler <stefan.huchler@mail.de>, help-gnu-emacs@gnu.org
Subject: RE: beginnerquestion (nconc)
Date: Fri, 17 Mar 2017 10:20:55 -0700 (PDT) [thread overview]
Message-ID: <3fe53f75-8c02-4b18-bb9e-401bb1ffe0c1@default> (raw)
In-Reply-To: <87k27nzvo7.fsf@mail.de>
> if I have to reverse, wouldnt it be easier that there is some
> sort of: (yreverse sequence) that alters the sequence directly,
> or overwrites it. instead of: (setq sequence (nreverse sequence))
You can write macros to do this kind of thing, if you think
using the usual Lisp cliches is ugly.
(defmacro my-list-var-reverse (list-var)
"Set variable LIST-VAR to the reverse of its value.
LIST-VAR is a symbol whose `symbol-value' is a list."
`(setq ,list-var (nreverse ,list-var)))
(setq aaa '(1 2 3 4))
(my-list-var-reverse 'aaa)
(symbol-value 'aaa) ; ==> (4 3 2 1)
(`nreverse' acts only on lists, not on sequences in general.)
next prev parent reply other threads:[~2017-03-17 17:20 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-17 5:58 beginnerquestion (nconc) Stefan Huchler
2017-03-17 7:33 ` Thien-Thi Nguyen
2017-03-17 8:52 ` Thien-Thi Nguyen
2017-03-17 14:19 ` Stefan Huchler
2017-03-17 14:48 ` tomas
2017-03-17 14:42 ` Yuri Khan
2017-03-17 16:59 ` Stefan Huchler
2017-03-17 17:20 ` Drew Adams [this message]
2017-03-17 17:32 ` Drew Adams
2017-03-18 2:15 ` Stefan Monnier
2017-03-21 16:47 ` Stefan Huchler
2017-03-21 16:59 ` Stefan Huchler
2017-03-21 20:14 ` John Mastro
2017-03-22 0:32 ` Stefan Huchler
2017-03-22 15:02 ` Michael Heerdegen
2017-03-22 19:00 ` John Mastro
2017-03-21 11:05 ` Michael Heerdegen
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