From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Drew Adams" Newsgroups: gmane.emacs.help Subject: RE: How to remove verbosity from the data passing mechanism using alist or plist ? Date: Tue, 7 Dec 2010 07:14:18 -0800 Message-ID: References: <87lj43at0i.fsf@ambire.localdomain> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1291735039 23236 80.91.229.12 (7 Dec 2010 15:17:19 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Tue, 7 Dec 2010 15:17:19 +0000 (UTC) To: "'PJ Weisberg'" , "'help-gnu-emacs'" Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Tue Dec 07 16:17:15 2010 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1PPzI3-0002zQ-9S for geh-help-gnu-emacs@m.gmane.org; Tue, 07 Dec 2010 16:17:15 +0100 Original-Received: from localhost ([127.0.0.1]:42508 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PPzI2-0003SC-N0 for geh-help-gnu-emacs@m.gmane.org; Tue, 07 Dec 2010 10:17:14 -0500 Original-Received: from [140.186.70.92] (port=49905 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PPzHI-0003Qs-Fc for Help-gnu-emacs@gnu.org; Tue, 07 Dec 2010 10:16:53 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PPzGz-00079J-QZ for Help-gnu-emacs@gnu.org; Tue, 07 Dec 2010 10:16:28 -0500 Original-Received: from rcsinet10.oracle.com ([148.87.113.121]:51439) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PPzGz-00078w-Le for Help-gnu-emacs@gnu.org; Tue, 07 Dec 2010 10:16:09 -0500 Original-Received: from rcsinet15.oracle.com (rcsinet15.oracle.com [148.87.113.117]) by rcsinet10.oracle.com (Switch-3.4.2/Switch-3.4.2) with ESMTP id oB7FG6qN027073 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 7 Dec 2010 15:16:08 GMT Original-Received: from acsmt354.oracle.com (acsmt354.oracle.com [141.146.40.154]) by rcsinet15.oracle.com (Switch-3.4.2/Switch-3.4.1) with ESMTP id oB7FG5pC010412; Tue, 7 Dec 2010 15:16:05 GMT Original-Received: from abhmt006.oracle.com by acsmt353.oracle.com with ESMTP id 833093481291734862; Tue, 07 Dec 2010 07:14:22 -0800 Original-Received: from dradamslap1 (/10.159.219.164) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 07 Dec 2010 07:14:21 -0800 X-Mailer: Microsoft Office Outlook 11 In-Reply-To: Thread-Index: AcuV5LYTesTuzLJOR1Odo9NpxIEZ6AAOmbPA X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5994 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:75531 Archived-At: > those things that look like lists but have dots in them are > a result of someone abusing "cons" to make a cons cell whose > 'next' pointer points to something other than the next cons > cell in a list. Actually this is not an abuse of poor little `cons'. ;-) The list `(x)' is in fact an example of such "abusive" behavior: the cdr ("next") is the symbol `nil', which is an atom, not a cons cell: `(x . nil)'. It is correct to say that cons cells are used to build lists, and that that is their most common use. And that a list is either `nil' or a cons cell whose cdr is a list. But it is also correct that some cons cells are not lists, i.e., do not have a list as their cdr. `cons' is untyped wrt its parameters. It is not only the first parameter (the car) that need not be a list, but also the second (the cdr).