From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Neil Jerram Newsgroups: gmane.lisp.guile.devel Subject: Re: truth of %nil Date: Thu, 17 Sep 2009 22:21:23 +0100 Message-ID: <87my4tgtd8.fsf@ossau.uklinux.net> References: <87k52uvhnt.fsf@arudy.ossau.uklinux.net> <873a9hl5uf.fsf@arudy.ossau.uklinux.net> <4A4B0619.5070006@domob.eu> <87ljn8rrv9.fsf@arudy.ossau.uklinux.net> <20090705130725.GA2021@fibril.netris.org> <87my5hy2yv.fsf@arudy.ossau.uklinux.net> <20090830141100.GA2255@fibril.netris.org> <87r5uqnx4c.fsf@arudy.ossau.uklinux.net> <20090902155727.GA3310@fibril.netris.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1253222513 23766 80.91.229.12 (17 Sep 2009 21:21:53 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 17 Sep 2009 21:21:53 +0000 (UTC) Cc: Andy Wingo , Daniel Kraft , guile-devel To: Mark H Weaver Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Thu Sep 17 23:21:45 2009 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MoOQD-0005xG-Gh for guile-devel@m.gmane.org; Thu, 17 Sep 2009 23:21:45 +0200 Original-Received: from localhost ([127.0.0.1]:56890 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MoOQC-00046F-Pq for guile-devel@m.gmane.org; Thu, 17 Sep 2009 17:21:44 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MoOQ1-00042Z-6P for guile-devel@gnu.org; Thu, 17 Sep 2009 17:21:33 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MoOPw-00040Z-E3 for guile-devel@gnu.org; Thu, 17 Sep 2009 17:21:32 -0400 Original-Received: from [199.232.76.173] (port=33651 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MoOPw-00040S-7f for guile-devel@gnu.org; Thu, 17 Sep 2009 17:21:28 -0400 Original-Received: from mail3.uklinux.net ([80.84.72.33]:49837) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MoOPv-0006sT-SY for guile-devel@gnu.org; Thu, 17 Sep 2009 17:21:28 -0400 Original-Received: from arudy (host86-147-112-99.range86-147.btcentralplus.com [86.147.112.99]) by mail3.uklinux.net (Postfix) with ESMTP id CE1021F67AE; Thu, 17 Sep 2009 22:21:24 +0100 (BST) Original-Received: from arudy (arudy [127.0.0.1]) by arudy (Postfix) with ESMTP id D4F5E38021; Thu, 17 Sep 2009 22:21:23 +0100 (BST) In-Reply-To: <20090902155727.GA3310@fibril.netris.org> (Mark H. Weaver's message of "Wed, 2 Sep 2009 11:57:27 -0400") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.4-2.6 X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:9340 Archived-At: Mark H Weaver writes: > Certainly writing (a b c . #nil) as (a b c) would be most natural and > convenient, and maybe it's the best compromise, but I'm not entirely > sure it's safe. > > What if we have an association list mapping symbols to booleans that > came from elisp? Such a alist might look something like > ((a . #t) (b . #nil)), and can reasonably be assumed to be written > and then read back in, but doing so would then result in > ((a . #t) (b . ())), magically changing the false to a true. Hmmm... From the elisp point of view it's still false, of course. From the scheme point of view your point stands. > This also violates the idea the CARs and CDRs should be treated the > same way. Also a good point. > I'm tempted to suggest that "write" should write (a . #nil) as > "(a . #nil)", and "display" should write it as "(a)". For now I'm happy with any reasonable position (such as this), because I don't think we've got any data to help decide between the options. Hopefully it won't be too long before we have some real non-trival Guile/Scheme/Elisp interactions. Neil