From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: border1.nntp.dca3.giganews.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!ottix-news.ottix.net!newsswitch.lcs.mit.edu!nntp.TheWorld.com!.POSTED!not-for-mail From: Robert A Duff Newsgroups: comp.lang.ada Subject: Re: The future of Spark . Spark 2014 : a wreckage Date: Tue, 09 Jul 2013 18:51:36 -0400 Organization: The World Public Access UNIX, Brookline, MA Message-ID: References: <87hag4ahu5.fsf@mid.deneb.enyo.de> <1rbbala6i0jcl$.dswyfcctu6vs$.dlg@40tude.net> NNTP-Posting-Host: shell01.theworld.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: pcls7.std.com 1373410296 12635 192.74.137.71 (9 Jul 2013 22:51:36 GMT) X-Complaints-To: abuse@TheWorld.com NNTP-Posting-Date: Tue, 9 Jul 2013 22:51:36 +0000 (UTC) User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (irix) Cancel-Lock: sha1:flL4YimvySIoyccIXx5mxbwsBlY= X-Original-Bytes: 1754 Xref: number.nntp.dca.giganews.com comp.lang.ada:182406 Date: 2013-07-09T18:51:36-04:00 List-Id: "Dmitry A. Kazakov" writes: > On Mon, 08 Jul 2013 22:59:30 +0200, Florian Weimer wrote: >> This is nothing new. Boolean implication p → q is already written as >> P <= Q in Ada. > > Where? > > It would be plain wrong, ... Less-or-equal on Booleans is indeed equivalent to implication. But that's a hack. Considering Booleans as ordered is questionable -- I never heard of such a thing in mathematical logic. >...because logical implication (not P or Q) must be > denoted as P => Q. It must be? In Eiffel, it is denoted by the "implies" keyword. In Ada 2012, one writes "(if P then Q)", which is shorthand for "(if P then Q else True)". - Bob