From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Pascal J. Bourguignon" Newsgroups: gmane.emacs.help Subject: Re: How to flatten a one-level-deep list? Date: Wed, 18 May 2016 19:52:21 +0200 Organization: Informatimago Message-ID: <8737pffe3u.fsf@kuiper.lan.informatimago.com> References: <877fes54pz.fsf@mbork.pl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1464883278 13449 80.91.229.3 (2 Jun 2016 16:01:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 2 Jun 2016 16:01:18 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Thu Jun 02 18:01:16 2016 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1b8V3b-0000nN-QO for geh-help-gnu-emacs@m.gmane.org; Thu, 02 Jun 2016 18:01:15 +0200 Original-Received: from localhost ([::1]:48208 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b8V3b-0004uY-33 for geh-help-gnu-emacs@m.gmane.org; Thu, 02 Jun 2016 12:01:15 -0400 Original-Path: usenet.stanford.edu!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 34 Original-X-Trace: individual.net aNezVRgDFEhs2okezhmk2wCGu9jrphlM8fQv5+kQVaqLZNQwl5 Cancel-Lock: sha1:ZGIxZGI4M2RlMmI3Y2FlNDU0ZTgzZmY1ODI1Mjc1ODlkYzc1MThhOQ== sha1:K0dT3FNSnv8lnDhDAbF7dDmb+hU= Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwAQMAAABtzGvEAAAABlBMVEUAAAD///+l2Z/dAAAA oElEQVR4nK3OsRHCMAwF0O8YQufUNIQRGIAja9CxSA55AxZgFO4coMgYrEDDQZWPIlNAjwq9 033pbOBPtbXuB6PKNBn5gZkhGa86Z4x2wE67O+06WxGD/HCOGR0deY3f9Ijwwt7rNGNf6Oac l/GuZTF1wFGKiYYHKSFAkjIo1b6sCYS1sVmFhhhahKQssRjRT90ITWUk6vvK3RsPGs+M1RuR mV+hO/VvFAAAAABJRU5ErkJggg== X-Accept-Language: fr, es, en User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) Original-Xref: usenet.stanford.edu gnu.emacs.help:217794 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.org gmane.emacs.help:110231 Archived-At: writes: > On Wed, May 18, 2016 at 07:12:56AM +0200, Marcin Borkowski wrote: >> Hi, >> >> I have a list of lists of atoms, and I want to have a flat list >> containing these atoms. I could use -flatten from dash.el, but I'd >> prefer not to introduce such a dependency for this one function alone. >> Is there anything *in core Emacs* to do it, or should I just write my >> own version? > > (setq l '((a b c) (d e f) (g h i))) > (apply 'append l) > => (a b c d e f g h i) > > No idea whether performance or edge cases match your requirements, > though :) append will refer to the last list in that literal list, thus making the result half literal. This may be a problem or not, depending on how you use this result. You can use concatenate (cl-concatenate) instead, if you want to copy even the last subsequence: (apply 'concatenate 'list l) --> (a b c d e f g h i) -- __Pascal Bourguignon__ http://www.informatimago.com/ “The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment.” -- Carl Bass CEO Autodesk