From: Thien-Thi Nguyen <ttn@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: some more material on the Lisp data/code psychedelia
Date: Sat, 04 Jan 2014 21:13:26 +0100 [thread overview]
Message-ID: <87ob3rpkt5.fsf@zigzag.favinet> (raw)
In-Reply-To: <87sit31qt7.fsf@nl106-137-194.student.uu.se> (Emanuel Berg's message of "Sat, 04 Jan 2014 20:37:15 +0100")
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() Emanuel Berg <embe8573@student.uu.se>
() Sat, 04 Jan 2014 20:37:15 +0100
(defun increment-last (l)
(interactive)
(if (not l) '()
(let ((hd (car l))
(tl (cdr l)) )
(if (not tl)
(list (+ 1 hd))
(cons hd (increment-last tl) )))))
You can also use ‘last’ and ‘setcar’ (via ‘incf’) for this:
(defun increment-last (ls)
(when ls
(incf (car (last ls)))
ls))
Non-recursive means less stack required for long forms. Destructive
style is sketchy but the func is already squarely in DWR territory...
--
Thien-Thi Nguyen
GPG key: 4C807502
(if you're human and you know it)
read my lisp: (responsep (questions 'technical)
(not (via 'mailing-list)))
=> nil
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next prev parent reply other threads:[~2014-01-04 20:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-04 19:37 some more material on the Lisp data/code psychedelia Emanuel Berg
2014-01-04 20:13 ` Thien-Thi Nguyen [this message]
[not found] ` <mailman.11016.1388866201.10748.help-gnu-emacs@gnu.org>
2014-01-04 20:24 ` Emanuel Berg
2014-01-04 23:40 ` Emanuel Berg
2014-01-17 1:29 ` Emanuel Berg
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