From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: HiPhish Newsgroups: gmane.lisp.guile.user Subject: Re: A value for "nothing" Date: Mon, 27 Aug 2018 10:24:26 +0200 Message-ID: <1545468.AJPqrIK6VD@aleksandar-ixtreme-m5740> References: <21036238.c6yQEfjfIL@aleksandar-ixtreme-m5740> <8840615.kRvQfVdCvZ@aleksandar-ixtreme-m5740> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit X-Trace: blaine.gmane.org 1535358172 15014 195.159.176.226 (27 Aug 2018 08:22:52 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 27 Aug 2018 08:22:52 +0000 (UTC) Cc: guile-user@gnu.org To: John Cowan Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Mon Aug 27 10:22:47 2018 Return-path: Envelope-to: guile-user@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fuCnL-0003kq-3S for guile-user@m.gmane.org; Mon, 27 Aug 2018 10:22:43 +0200 Original-Received: from localhost ([::1]:51951 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuCpR-00077j-8C for guile-user@m.gmane.org; Mon, 27 Aug 2018 04:24:53 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:49770) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuCp7-00077d-CE for guile-user@gnu.org; Mon, 27 Aug 2018 04:24:33 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fuCp4-0006lQ-4n for guile-user@gnu.org; Mon, 27 Aug 2018 04:24:33 -0400 Original-Received: from mout02.posteo.de ([185.67.36.66]:45003) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fuCp3-0006jf-Qf for guile-user@gnu.org; Mon, 27 Aug 2018 04:24:30 -0400 Original-Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 6286321116 for ; Mon, 27 Aug 2018 10:24:27 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1535358268; bh=FLWs2Zi2F8nyZlbeGXB0jSjRcaWSMhmYSxv4t7Lxnso=; h=From:To:Cc:Subject:Date:From; b=RWqwKQhESvpliSwAHoOk535OoQepNcLqyTeXJZuhVP6zrBVca3prIupH8/VO+CYF9 mmNifQlXX5a+r+DErC2FijToYiyZq3TjtaJBSCXC8kLYbLvI9Bzkc6Iub7AFy+4BJd 1LyFxXoQHohKKJzfj2PqhxfhISlCbqEQDX5A6uUjyB/KyAfJOAuRbiKwttrzQjuIbG eeSQbrP+mgJLeUpVOzdjVqNoND7jnDzAeRDDWLH5UAWajEgrh2OeZsKuoS64Jnnedm 1nC0flYepa6pFiZJanTvAIuO4xMEl3CID4yjQMb6BNutrhpBLzowgp5tMHzcI1RgQG CD/iFHx7G53Yg== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 41zQ0W00rgz9rxP; Mon, 27 Aug 2018 10:24:26 +0200 (CEST) In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 185.67.36.66 X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-user-bounces+guile-user=m.gmane.org@gnu.org Original-Sender: "guile-user" Xref: news.gmane.org gmane.lisp.guile.user:14776 Archived-At: Yes, this sounds like the best solution so far. On Sonntag, 26. August 2018 23:07:26 CEST you wrote: > The eq? predicate is able to distinguish the three. But I think using a > singleton record is best: > > (define-record-type ( nil? make-nil)) > (define nil (make-nil)) > > and thene export njil and nil? but not ni> or make-nil.