From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andy Wingo Newsgroups: gmane.lisp.guile.devel Subject: Re: truth of %nil Date: Tue, 30 Jun 2009 00:11:28 +0200 Message-ID: References: <87k52uvhnt.fsf@arudy.ossau.uklinux.net> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1246313522 6459 80.91.229.12 (29 Jun 2009 22:12:02 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 29 Jun 2009 22:12:02 +0000 (UTC) Cc: guile-devel To: Neil Jerram Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Tue Jun 30 00:11:55 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 1MLP4s-0000ca-5k for guile-devel@m.gmane.org; Tue, 30 Jun 2009 00:11:54 +0200 Original-Received: from localhost ([127.0.0.1]:58889 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MLP4r-00084Z-Hh for guile-devel@m.gmane.org; Mon, 29 Jun 2009 18:11:53 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MLP4R-0007Wu-Bj for guile-devel@gnu.org; Mon, 29 Jun 2009 18:11:27 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MLP4M-0007NO-6M for guile-devel@gnu.org; Mon, 29 Jun 2009 18:11:26 -0400 Original-Received: from [199.232.76.173] (port=35529 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MLP4M-0007N0-18 for guile-devel@gnu.org; Mon, 29 Jun 2009 18:11:22 -0400 Original-Received: from a-sasl-quonix.sasl.smtp.pobox.com ([208.72.237.25]:55891 helo=sasl.smtp.pobox.com) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MLP4L-0000TT-Oi for guile-devel@gnu.org; Mon, 29 Jun 2009 18:11:21 -0400 Original-Received: from localhost.localdomain (unknown [127.0.0.1]) by a-sasl-quonix.sasl.smtp.pobox.com (Postfix) with ESMTP id CEF7D24A32; Mon, 29 Jun 2009 18:11:10 -0400 (EDT) Original-Received: from unquote (unknown [88.17.129.121]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by a-sasl-quonix.sasl.smtp.pobox.com (Postfix) with ESMTPSA id 3133824A2B; Mon, 29 Jun 2009 18:11:08 -0400 (EDT) In-Reply-To: <87k52uvhnt.fsf@arudy.ossau.uklinux.net> (Neil Jerram's message of "Mon, 29 Jun 2009 22:44:54 +0100") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.92 (gnu/linux) X-Pobox-Relay-ID: C09596AC-64F9-11DE-A320-DC021A496417-02397024!a-sasl-quonix.pobox.com X-detected-operating-system: by monty-python.gnu.org: Solaris 10 (beta) 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:8803 Archived-At: On Mon 29 Jun 2009 23:44, Neil Jerram writes: > Andy Wingo writes: > >> scheme@(guile-user)> (if %nil 1 2) >> 1 >> >> #define scm_is_false(x) (scm_is_eq ((x), SCM_BOOL_F) || SCM_NILP (x)) > Seems wrong to me. In Scheme #f should be the only false value. > What's the argument for %nil being false in Scheme code? I thought the original plan regarding %nil and #f and '() was that %nil wasn't supposed to be seen normally from Scheme, and for that reason (and (null? %nil) (not %nil)) would not be a problem. Guile has treated %nil as false for quite some time: scheme@(guile-user)> ,o interp #t scheme@(guile-user)> (if %nil 1 2) $1 = 2 Andy -- http://wingolog.org/