From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.help Subject: Re: Why doesn't nconc change my variable? Date: Sun, 05 Oct 2014 11:35:35 +0200 Message-ID: <87wq8eluzc.fsf@wmi.amu.edu.pl> References: <87zjdbmg38.fsf@kuiper.lan.informatimago.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1412501772 18036 80.91.229.3 (5 Oct 2014 09:36:12 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 5 Oct 2014 09:36:12 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sun Oct 05 11:36:06 2014 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 1XaiEX-0003PP-Ih for geh-help-gnu-emacs@m.gmane.org; Sun, 05 Oct 2014 11:36:05 +0200 Original-Received: from localhost ([::1]:46854 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XaiEX-0007wb-1Q for geh-help-gnu-emacs@m.gmane.org; Sun, 05 Oct 2014 05:36:05 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54849) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XaiEI-0007wW-TA for help-gnu-emacs@gnu.org; Sun, 05 Oct 2014 05:35:56 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XaiED-0000kt-7q for help-gnu-emacs@gnu.org; Sun, 05 Oct 2014 05:35:50 -0400 Original-Received: from msg.wmi.amu.edu.pl ([2001:808:114:2::50]:41055) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XaiED-0000kE-0P for help-gnu-emacs@gnu.org; Sun, 05 Oct 2014 05:35:45 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by msg.wmi.amu.edu.pl (Postfix) with ESMTP id 5BA1E5077D for ; Sun, 5 Oct 2014 11:35:43 +0200 (CEST) Original-Received: from msg.wmi.amu.edu.pl ([127.0.0.1]) by localhost (msg.wmi.amu.edu.pl [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id URt8v0+mhAxP for ; Sun, 5 Oct 2014 11:35:43 +0200 (CEST) Original-Received: from localhost (111-128.echostar.pl [213.156.111.128]) by msg.wmi.amu.edu.pl (Postfix) with ESMTPSA id 219195077B for ; Sun, 5 Oct 2014 11:35:42 +0200 (CEST) In-reply-to: <87zjdbmg38.fsf@kuiper.lan.informatimago.com> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:808:114:2::50 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:100281 Archived-At: On 2014-10-05, at 03:59, Pascal J. Bourguignon wrote: > Marcin Borkowski writes: > >> Hi list, >> >> I don't get it. > > () is actually read as the symbol nil. > Symbols are symbols, and not cons cells. > You cannot transform a symbol into a cons cell. > It is impossible for any function to transform nil into a cons cell. > > And vice-versa, it is impossible to transform a cons cell into a symbol > such as nil. This is the reason why you should also use setf when > deleting elements from a list: > > (setf list (delete e list)) I still don't understand. What if I used (list) to generate an empty list instead of () or nil? The results seem to be still the same. Best, -- Marcin Borkowski http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski Adam Mickiewicz University