From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Newsgroups: gmane.lisp.guile.user Subject: Re: A value for "nothing" Date: Mon, 27 Aug 2018 10:04:15 +0200 Message-ID: <20180827080415.GB10407@tuxteam.de> References: <21036238.c6yQEfjfIL@aleksandar-ixtreme-m5740> <87sh30vqmm.fsf@netris.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; x-action=pgp-signed Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1535357776 16767 195.159.176.226 (27 Aug 2018 08:16:16 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 27 Aug 2018 08:16:16 +0000 (UTC) User-Agent: Mutt/1.5.21 (2010-09-15) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Mon Aug 27 10:16:12 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 1fuCh2-0004Ez-4L for guile-user@m.gmane.org; Mon, 27 Aug 2018 10:16:12 +0200 Original-Received: from localhost ([::1]:51897 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuCj8-0001gQ-ES for guile-user@m.gmane.org; Mon, 27 Aug 2018 04:18:22 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:47410) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fuCiE-0001c5-EI for guile-user@gnu.org; Mon, 27 Aug 2018 04:17:29 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fuCVU-0000al-PY for guile-user@gnu.org; Mon, 27 Aug 2018 04:04:20 -0400 Original-Received: from mail.tuxteam.de ([5.199.139.25]:47687) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fuCVU-0000a1-HJ for guile-user@gnu.org; Mon, 27 Aug 2018 04:04:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tuxteam.de; s=mail; h=From:In-Reply-To:Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID:Subject:To:Date; bh=oU2K/7G38NqWjkS8687jyBDck3CUHgHKhy0x5eW/Fok=; b=GryZRiFdwrOLRL3VQnmv6TmfXn5ueIrodGmApJXASgqxJ+H7sq2Ilojfhv51zH9Z23Ce55xZP0/p+JIZ7J2jlInQBLdZt+sRq4fW1rIGe2yP4mH+IsDWnZ16IFt/KGwKAia1fpPwri+rPmjz4wxCBC9+Gckw37m1R6R9w6iWVVRwF1EcXKz+IucqvJ5lcx9K78zo2e1Bel0jJvK+Bmd5x7c8HO+plon5lEmU8tCFjLP8x1J5OBeG8SRSnRlAoikvrvpg9c6cqzgkM3bq8oCitheXSUyk0y8qOSdqHvkblOOK5+t8bi2Frm1qFBLq9NyiQPRuYGBTxI+3RmgxwFxWYw==; Original-Received: from tomas by mail.tuxteam.de with local (Exim 4.80) (envelope-from ) id 1fuCVT-0002pz-Dh for guile-user@gnu.org; Mon, 27 Aug 2018 10:04:15 +0200 In-Reply-To: <87sh30vqmm.fsf@netris.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 5.199.139.25 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:14775 Archived-At: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sun, Aug 26, 2018 at 04:07:13PM -0400, Mark H Weaver wrote: [...] > It's true that Guile historically has a special object distinct from all > other objects, which (if #f #f) and various other expressions return, > and which prints as "#". > > However, the fact that some existing code out there might depend on the > existence of this distinguished object, and that certain expressions in > Guile return it, is historical baggage which carries non-zero costs as > we move to native code generation. > > I would also argue that it carries a terrible conceptual cost, in that > it leads to confusion between the concept of a truly unspecified return > value (as in R5RS) and this distinguished value in Guile that is called > "the unspecified value", a non-sensical notion. > > I would also avoid Guile's #nil. That is a very special value, for one > purpose relating to Elisp compatibility, and ideally it should not be > used for anything else. I must admit that I'm... pretty confused about this very prescriptive tone. Sorry. Cheers - -- tomás -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAluDsH8ACgkQBcgs9XrR2kZCMwCfQpgyL+cC38ZHKqhV0rAG02sq +WIAnjXIVutY/p0Q3nrbZjfNuVzhcDgY =/B5d -----END PGP SIGNATURE-----