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: 'length' function for lists and cons cells? Date: Sat, 23 Mar 2013 12:31:37 +0100 Organization: Informatimago Message-ID: <87boaapd2e.fsf@kuiper.lan.informatimago.com> References: <87sj3opjfw.fsf@kuiper.lan.informatimago.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1364051887 8858 80.91.229.3 (23 Mar 2013 15:18:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 23 Mar 2013 15:18:07 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sat Mar 23 16:18:34 2013 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 1UJQDJ-0007h3-N4 for geh-help-gnu-emacs@m.gmane.org; Sat, 23 Mar 2013 16:18:33 +0100 Original-Received: from localhost ([::1]:39475 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UJQCw-0002mR-2T for geh-help-gnu-emacs@m.gmane.org; Sat, 23 Mar 2013 11:18:10 -0400 Original-Path: usenet.stanford.edu!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 42 Original-X-Trace: individual.net Pj2wPYtmDUlO3RI270qUDAiDbBBbhEKYg3j22lK7BIkr16P9Fa Cancel-Lock: sha1:MGI3ZTg5NWZjOTQ2NGMzYjA5Njc0MTc0ZjJmOWZmNDkzYjEzMTQxYw== sha1:9t30O9Y5zwTWZ6sYXPza5U06ysM= 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/24.2 (gnu/linux) Original-Xref: usenet.stanford.edu gnu.emacs.help:197413 X-Mailman-Approved-At: Sat, 23 Mar 2013 11:17:49 -0400 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 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-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:89685 Archived-At: Thorsten Jolitz writes: > "Pascal J. Bourguignon" writes: > >> I don't understand what you want to do. > > well, avoid the errors I get when mapping alists with true lists and > cons cells as elements with functions like 'lenght of 'cdr etc. > >> You can use length and dolist on alists and it will work perfectly: >> (length '((a . 1) (b . 2) (c . 3))) >> --> 3 > > yes, but, when mapping the elements: > > ,------------------------------------------------------------ > | (length '(a . 1)) This is not an a-list, this is a dotted-list. Note that a-list entries can be proper-list, if the value is a proper-list, or circular lists, if the value is a circular list: (defvar *a* '((proper-list . (un one uno)) (circular-list . (deux . #1=(two dos . #1#))) (dotted-list . (un . deux)) (single-cell-dotted-list . single))) *a* --> ((proper-list un one uno) (circular-list deux . #1=(two dos . #1#)) (dotted-list un . deux) (single-cell-dotted-list . single)) (cdr (assoc 'proper-list *a*)) --> (un one uno) (cdr (assoc 'circular-list *a*)) --> (deux . #1=(two dos . #1#)) (cdr (assoc 'dotted-list *a*)) --> (un . deux) (cdr (assoc 'single-cell-dotted-list *a*)) --> single -- __Pascal Bourguignon__ http://www.informatimago.com/ A bad day in () is better than a good day in {}.