From mboxrd@z Thu Jan  1 00:00:00 1970
Path: news.gmane.org!not-for-mail
From: Barry Margolin <barmar@alum.mit.edu>
Newsgroups: gmane.emacs.help
Subject: Re: Why is booleanp defined this way?
Date: Fri, 17 Apr 2015 23:13:49 -0400
Organization: A noiseless patient Spider
Message-ID: <barmar-DE640A.23134917042015@88-209-239-213.giganet.hu>
References: <mailman.946.1429302909.904.help-gnu-emacs@gnu.org>
	<barmar-43C938.19204417042015@88-209-239-213.giganet.hu>
	<87lhhqnxip.fsf@debian.uxu>
	<87k2xamfkg.fsf@kuiper.lan.informatimago.com>
NNTP-Posting-Host: plane.gmane.org
X-Trace: ger.gmane.org 1429326935 17342 80.91.229.3 (18 Apr 2015 03:15:35 GMT)
X-Complaints-To: usenet@ger.gmane.org
NNTP-Posting-Date: Sat, 18 Apr 2015 03:15:35 +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 Apr 18 05:15:35 2015
Return-path: <help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org>
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 <help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org>)
	id 1YjJEE-000772-NJ
	for geh-help-gnu-emacs@m.gmane.org; Sat, 18 Apr 2015 05:15:34 +0200
Original-Received: from localhost ([::1]:44351 helo=lists.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org>)
	id 1YjJED-0004oo-Ml
	for geh-help-gnu-emacs@m.gmane.org; Fri, 17 Apr 2015 23:15:33 -0400
Original-Path: usenet.stanford.edu!news.kjsl.com!feeder.erje.net!1.eu.feeder.erje.net!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!barmar.motzarella.org!.POSTED!not-for-mail
Original-Newsgroups: gnu.emacs.help
Original-Lines: 22
Injection-Info: barmar.motzarella.org;
	posting-host="2be9e9f5dd9af768b8861af71b85fc28"; 
	logging-data="27239"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX1/6PCi8oCW9UrVrZ6Ng/B7h"
User-Agent: MT-NewsWatcher/3.5.3b3 (Intel Mac OS X)
Cancel-Lock: sha1:a+mxWTV0DPQ8UP1bjO7Dki7xOMA=
Original-Xref: usenet.stanford.edu gnu.emacs.help:211518
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 <help-gnu-emacs.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/help-gnu-emacs>,
	<mailto:help-gnu-emacs-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/help-gnu-emacs>
List-Post: <mailto:help-gnu-emacs@gnu.org>
List-Help: <mailto:help-gnu-emacs-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/help-gnu-emacs>,
	<mailto:help-gnu-emacs-request@gnu.org?subject=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:103800
Archived-At: <http://permalink.gmane.org/gmane.emacs.help/103800>

In article <87k2xamfkg.fsf@kuiper.lan.informatimago.com>,
 "Pascal J. Bourguignon" <pjb@informatimago.com> wrote:

> Emanuel Berg <embe8573@student.uu.se> writes:
> 
> > Barry Margolin <barmar@alum.mit.edu> writes:
> >
> >> (booleanp nil) => (nil t)
> >> (booleanp t) => (t)
> >> (booleanp something-else) => nil
> 
> And even if that was true, that would still be a valid implementation,
> since both (nil t) and (t) are generalized booleans that are true! 

That's what I said in my post. When used in a boolean context, a 
generalized boolean is fine. But it would be confusing when used in a 
REPL.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***