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 10:40:05 +0200 Message-ID: <15511073.3h7x93ioX3@aleksandar-ixtreme-m5740> References: <21036238.c6yQEfjfIL@aleksandar-ixtreme-m5740> <3467110.H24gZIzStD@aleksandar-ixtreme-m5740> <87ftz0vidc.fsf@netris.org> 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 1535359107 22142 195.159.176.226 (27 Aug 2018 08:38:27 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 27 Aug 2018 08:38:27 +0000 (UTC) Cc: guile-user@gnu.org To: Mark H Weaver Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Mon Aug 27 10:38:23 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 1fuD2T-0005df-Ha for guile-user@m.gmane.org; Mon, 27 Aug 2018 10:38:21 +0200 Original-Received: from localhost ([::1]:51997 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuD4Z-0007lF-S9 for guile-user@m.gmane.org; Mon, 27 Aug 2018 04:40:31 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:53537) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuD4H-0007kz-1V for guile-user@gnu.org; Mon, 27 Aug 2018 04:40:13 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fuD4D-00024Y-SP for guile-user@gnu.org; Mon, 27 Aug 2018 04:40:12 -0400 Original-Received: from mout01.posteo.de ([185.67.36.65]:39315) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fuD4D-00023N-Dg for guile-user@gnu.org; Mon, 27 Aug 2018 04:40:09 -0400 Original-Received: from submission (posteo.de [89.146.220.130]) by mout01.posteo.de (Postfix) with ESMTPS id E063F210C1 for ; Mon, 27 Aug 2018 10:40:06 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1535359206; bh=cjQfU3RkX7C6gwOFlHSQ6qBUL/oIPJE6w3A2Fh0Foe0=; h=From:To:Cc:Subject:Date:From; b=SE6+VRhMKGN6d9fwBjGZ/Tpp/G6fAAGtVXhssO1RpvIHwn4FZfc3xDfNkwQ2Y1Zf+ ZgJQDtf556boaqI0HR5Y1QbLQKMiAPk94E1Lz1n34kQh1mMIAAs0J6m6PrYy2XeOU4 4ATdnEIZzVBBsPvU6R8rc2W1d4OivOIZJr9iCUWBV1F+rIcsI3/jSuHDuZJeY7rEoR xFsCyghGAcB1eUSL2lJW6CNZeJ/N2TLcPZnTbD+AVTUPGtTW6ze0szL3byK6/amcGq SsvrqNwOgVXyIbAn1X34jXa90NZMGm1G6aBviGddso1pn82gzi+pVeWVsItKFT1bj5 1E4xspmJCmeqw== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 41zQLZ0dr2z6tmJ; Mon, 27 Aug 2018 10:40:05 +0200 (CEST) In-Reply-To: <87ftz0vidc.fsf@netris.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 185.67.36.65 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:14779 Archived-At: I think I understand: it just so happens that `(if #f #f)` evaluates to `#`, but it would still be valid if it evaluated to 5 or "roflcopter". > "The return value of a function that returns nothing" is a > self-contradictory notion, if you think about it :) I was under the impression that in Lisp any S-expression evaluates to *something*, even if that something is some junk value or "nothing". > I would suggest using a symbol. How about 'nil? I was considering the possibility of serialising symbols as strings, but then 'nil would be indistinguishable from the string "nil". The more I think about, the more a singleton instance of a custom record makes sense.