From lojban-out@lojban.org Fri Nov 23 03:34:35 2007 Return-Path: X-Sender: lojban-out@lojban.org X-Apparently-To: lojban@yahoogroups.com X-Received: (qmail 352 invoked from network); 23 Nov 2007 11:34:34 -0000 X-Received: from unknown (66.218.67.97) by m52.grp.scd.yahoo.com with QMQP; 23 Nov 2007 11:34:34 -0000 X-Received: from unknown (HELO mail1.sea5.speakeasy.net) (69.17.117.3) by mta18.grp.scd.yahoo.com with SMTP; 23 Nov 2007 11:34:34 -0000 X-Received: (qmail 3888 invoked from network); 23 Nov 2007 11:34:34 -0000 X-Received: from chain.digitalkingdom.org ([64.81.66.169]) (envelope-sender ) by mail1.sea5.speakeasy.net (qmail-ldap-1.03) with AES256-SHA encrypted SMTP for ; 23 Nov 2007 11:34:34 -0000 X-Received: from lojban-out by chain.digitalkingdom.org with local (Exim 4.68) (envelope-from ) id 1IvWnb-0008O1-F3 for lojban@yahoogroups.com; Fri, 23 Nov 2007 03:34:27 -0800 X-Received: from chain.digitalkingdom.org ([64.81.66.169]) by chain.digitalkingdom.org with esmtp (Exim 4.68) (envelope-from ) id 1IvWg6-0007sV-6W; Fri, 23 Nov 2007 03:27:04 -0800 X-Received: with ECARTIS (v1.0.0; list lojban-list); Fri, 23 Nov 2007 03:13:43 -0800 (PST) X-Received: from nobody by chain.digitalkingdom.org with local (Exim 4.68) (envelope-from ) id 1IvWTP-0007sG-Tq for lojban-list-real@lojban.org; Fri, 23 Nov 2007 03:13:36 -0800 X-Received: from subvert-the-dominant-paradigm.net ([206.123.113.154]) by chain.digitalkingdom.org with esmtp (Exim 4.68) (envelope-from ) id 1IvWSy-0007px-Q1 for lojban-list@lojban.org; Fri, 23 Nov 2007 03:13:23 -0800 X-Received: from [61.247.251.10] (helo=[192.168.2.107]) by subvert-the-dominant-paradigm.net with esmtpsa (TLS-1.0:RSA_ARCFOUR_MD5:16) (Exim 4.60) (envelope-from ) id 1IvWSd-0005Ri-RQ; Fri, 23 Nov 2007 11:12:40 +0000 Cc: pdf23ds@gmail.com In-Reply-To: <925d17560710310926k5485f82fv9191f290fa7bc807@mail.gmail.com> References: <737b61f30710301744x530646c8q748ccb5190ec3eee@mail.gmail.com> <925d17560710310630te45f3dbs210159dcc8143a6d@mail.gmail.com> <737b61f30710310839w56198f5eid7d5ba0890011812@mail.gmail.com> <925d17560710310926k5485f82fv9191f290fa7bc807@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Date: Fri, 23 Nov 2007 16:49:48 +0530 Message-Id: <1195816788.18863.11.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.3 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by Ecartis X-Spam-Score: -0.0 X-Spam-Score-Int: 0 X-Spam-Bar: / X-archive-position: 13962 X-ecartis-version: Ecartis v1.0.0 Errors-to: lojban-list-bounce@lojban.org X-original-sender: jewel@subvert-the-dominant-paradigm.net X-list: lojban-list X-Spam-Score: -0.0 X-Spam-Score-Int: 0 X-Spam-Bar: / To: lojban@yahoogroups.com X-Originating-IP: 69.17.117.3 X-eGroups-Msg-Info: 1:12:0:0:0 X-eGroups-From: John Leuner From: John Leuner Reply-To: jewel@subvert-the-dominant-paradigm.net Subject: [lojban] Re: PEG left recursive definitions X-Yahoo-Group-Post: member; u=116389790; y=aH_xulfapLVLrn1CS_MDqrzZnKoBkveOcfazFjfN2_TdqNlPiw X-Yahoo-Profile: lojban_out X-Yahoo-Message-Num: 28441 Here is a discussion on left-recursion in peg parsers: http://www.mail-archive.com/peg@lists.csail.mit.edu/msg00086.html John On Wed, 2007-10-31 at 13:26 -0300, Jorge Llambías wrote: > On 10/31/07, Chris Capel wrote: > > > > Do you not think that the grammar definition itself would be better > > expressed with explicit left-recursion? > > Yes, I do, for the cases of left associativity. So for example the > left recursive: > > sumti-2 <- (sumti-2 joik-ek)? sumti-3 > > would reflect the left associativity better than the current: > > sumti-2 <- sumti-3 (joik-ek sumti-3)* > > > > > expr <- expr '?' expr ':' expr / 'x' > > > which would not be allowed in PEG. > > > > Well, "not allowed" in most implementations of PEG. (Although direct > > left recursion *is* rewritten automatically in Pappy.) But since it's > > isomorphic (i.e. identical after rewriting) to a non-left-recursive > > definition, I don't see why you'd say it's not allowed at all. > > I probably used the wrong words. I don't know much more about > this than what I learned from the Lojban PEG. I meant it would not be > allowed in Robin's implementation. > > mu'o mi'e xorxes > > > To unsubscribe from this list, send mail to lojban-list-request@lojban.org > with the subject unsubscribe, or go to http://www.lojban.org/lsg2/, or if > you're really stuck, send mail to secretary@lojban.org for help. > To unsubscribe from this list, send mail to lojban-list-request@lojban.org with the subject unsubscribe, or go to http://www.lojban.org/lsg2/, or if you're really stuck, send mail to secretary@lojban.org for help.