From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Maciek Godek" Newsgroups: gmane.lisp.guile.user Subject: Unspecified? Date: Fri, 14 Nov 2008 11:38:40 +0100 Message-ID: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1226659140 1123 80.91.229.12 (14 Nov 2008 10:39:00 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 14 Nov 2008 10:39:00 +0000 (UTC) To: guile-user@gnu.org Original-X-From: guile-user-bounces+guile-user=m.gmane.org@gnu.org Fri Nov 14 11:40:01 2008 Return-path: Envelope-to: guile-user@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1L0w5n-0003WS-RZ for guile-user@m.gmane.org; Fri, 14 Nov 2008 11:40:00 +0100 Original-Received: from localhost ([127.0.0.1]:50798 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1L0w4f-0003Ni-E2 for guile-user@m.gmane.org; Fri, 14 Nov 2008 05:38:49 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1L0w4Z-0003MW-Fj for guile-user@gnu.org; Fri, 14 Nov 2008 05:38:43 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1L0w4X-0003LE-SO for guile-user@gnu.org; Fri, 14 Nov 2008 05:38:43 -0500 Original-Received: from [199.232.76.173] (port=41614 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1L0w4X-0003LB-KI for guile-user@gnu.org; Fri, 14 Nov 2008 05:38:41 -0500 Original-Received: from an-out-0708.google.com ([209.85.132.244]:24728) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1L0w4X-00072M-CH for guile-user@gnu.org; Fri, 14 Nov 2008 05:38:41 -0500 Original-Received: by an-out-0708.google.com with SMTP id c38so601594ana.21 for ; Fri, 14 Nov 2008 02:38:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:mime-version:content-type:content-transfer-encoding :content-disposition; bh=oBfGWKSYLBSCIe/6NXuQxv3rSwPy+DxY14F4sUyh5ZY=; b=Fs6rQSnVm7vLhl3ENWoK8dlYRMZ2QcqhYmb7X4h8fRWgA2R8rRji1I/8mjQSSN4UA+ whQ8Jg6iykcnhnVayRt5luid0EEGqlIC7F7emnkFRASiYyz3fhfNHI5mYREnzmNCX9vy hHMJlQblyn2sFVUk4pZYVnXX9kqX4n5JQyItg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type :content-transfer-encoding:content-disposition; b=rDlDcAPLTfhOQq5V26Lw2wShctSmQ1rOiDrp6JwX+EFqFRKTBe1RbT7iPe3uEMgutd /Sbe/FqzqUipYkUIc3f1judj1ygszesXl73PMGDXHdoHhv1FpczSNGKg+M2FAjSnGwnN oP4qm9KlkXfYfUFbMsfql0+sIPJhuUo5Tnn5U= Original-Received: by 10.100.144.11 with SMTP id r11mr422085and.24.1226659120331; Fri, 14 Nov 2008 02:38:40 -0800 (PST) Original-Received: by 10.100.250.20 with HTTP; Fri, 14 Nov 2008 02:38:40 -0800 (PST) Content-Disposition: inline X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 2) X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-user-bounces+guile-user=m.gmane.org@gnu.org Errors-To: guile-user-bounces+guile-user=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.user:6906 Archived-At: Hey all yoh! Is there any "official" way to check whether or not a function returns a (specified) value? As I ran into the problem, I quickly came with a workaround: (define unspecified (if #f #t)) which allows to define the most basic predicates: (define (unspecified? x) (eq? x unspecified)) (define (specified? x) (not (unspecified? x))) but I find it kinda surprising that these are not available by default in the system. Best regards M.