From lojban+bncCMqBsa7nERCal7HnBBoExng8vg@googlegroups.com Tue Nov 23 15:18:05 2010 Received: from mail-gw0-f61.google.com ([74.125.83.61]) by chain.digitalkingdom.org with esmtp (Exim 4.72) (envelope-from ) id 1PL27X-0004vZ-AP; Tue, 23 Nov 2010 15:18:05 -0800 Received: by gwj23 with SMTP id 23sf868742gwj.16 for ; Tue, 23 Nov 2010 15:17:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=beta; h=domainkey-signature:received:x-beenthere:received:received:received :received:received-spf:received:mime-version:received:received :in-reply-to:references:date:message-id:subject:from:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :sender:list-subscribe:list-unsubscribe:content-type; bh=EfqiLboHMNaJHF9bLdawEmoXUy+s95xAmWm+pDMbbAU=; b=ZXZohNKvEElK9o3KSwUUk3Y2SmYfwOG31m02iMi/SJeNK6S41+i8BtBVloDLMm3BX6 N6Qe6uaxtvEgcaf28FEYMCyuwFCULsGkBjlK8J83J44pX7OQzSE4cSAkK75vkc9jVy4P VhES6WmQ7Ry8j6FEXNhOqjAoSJl/ndfzUyvig= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlegroups.com; s=beta; h=x-beenthere:received-spf:mime-version:in-reply-to:references:date :message-id:subject:from:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:sender:list-subscribe :list-unsubscribe:content-type; b=sYK/VC7HigFQCOze+k9ze1hRAG/cowSPqwYEUfHDiHu6S0dwmi47+YE04mpC56iQ1s Hgq7Mxc+R1DAPbL77ZgEBMObgHRaCUfZdzVG6ekb1VzffdRmUrpZzuwMa273eBGbU9KH n0//OEZed1sVisoO4042Gw3nTppIGGV8tnOuE= Received: by 10.100.120.15 with SMTP id s15mr272642anc.54.1290554266093; Tue, 23 Nov 2010 15:17:46 -0800 (PST) X-BeenThere: lojban@googlegroups.com Received: by 10.231.76.165 with SMTP id c37ls1929704ibk.3.p; Tue, 23 Nov 2010 15:17:44 -0800 (PST) Received: by 10.231.35.131 with SMTP id p3mr4393164ibd.11.1290554264369; Tue, 23 Nov 2010 15:17:44 -0800 (PST) Received: by 10.231.35.131 with SMTP id p3mr4393163ibd.11.1290554264308; Tue, 23 Nov 2010 15:17:44 -0800 (PST) Received: from mail-iw0-f178.google.com (mail-iw0-f178.google.com [209.85.214.178]) by gmr-mx.google.com with ESMTP id j25si2701673ibb.0.2010.11.23.15.17.43; Tue, 23 Nov 2010 15:17:43 -0800 (PST) Received-SPF: pass (google.com: domain of oges007@gmail.com designates 209.85.214.178 as permitted sender) client-ip=209.85.214.178; Received: by mail-iw0-f178.google.com with SMTP id 1so10466217iwn.9 for ; Tue, 23 Nov 2010 15:17:43 -0800 (PST) MIME-Version: 1.0 Received: by 10.231.35.8 with SMTP id n8mr8907987ibd.73.1290554262782; Tue, 23 Nov 2010 15:17:42 -0800 (PST) Received: by 10.231.16.139 with HTTP; Tue, 23 Nov 2010 15:17:42 -0800 (PST) In-Reply-To: <20101123190157.GG10838@alice.local> References: <20101123184352.GE10838@alice.local> <20101123185211.GU9301@digitalkingdom.org> <20101123190157.GG10838@alice.local> Date: Wed, 24 Nov 2010 10:17:42 +1100 Message-ID: Subject: Re: [lojban] rp-expression-tail ordered choice with empty grouping From: Ross Ogilvie To: lojban X-Original-Sender: oges007@gmail.com X-Original-Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of oges007@gmail.com designates 209.85.214.178 as permitted sender) smtp.mail=oges007@gmail.com; dkim=pass (test mode) header.i=@gmail.com Reply-To: lojban@googlegroups.com Precedence: list Mailing-list: list lojban@googlegroups.com; contact lojban+owners@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: Sender: lojban@googlegroups.com List-Subscribe: , List-Unsubscribe: , Content-Type: multipart/alternative; boundary=0022150482bb6586b40495c094db --0022150482bb6586b40495c094db Content-Type: text/plain; charset=ISO-8859-1 I've been playing around with the mekso grammar recently. I think I have a rewrite, but I want to finish coding and check that it works as I want it to. I'll post tomorrow or the day after if people are interested. mi'e ros On Wed, Nov 24, 2010 at 6:01 AM, .alyn.post. wrote: > On Tue, Nov 23, 2010 at 10:52:11AM -0800, Robin Lee Powell wrote: > > On Tue, Nov 23, 2010 at 11:43:52AM -0700, .alyn.post. wrote: > > > What does the following production in the lojban grammar mean?: > > > > > > rp-expression-tail <- rp-expression operator rp-expression-tail / > > > () > > > > > > Do I understand that to mean 'the sequence of rp-expression, > > > operator, and rp-expression-tail OR nothing?' Could the above > > > also be expressed: > > > > > > rp-expression-tail <- (rp-expression operator rp-expression-tail)? > > > > > > And if so, why the odd way of specifying it? I'm weak on pitfalls > > > of recursive behavior in grammars, am I looking at a workaround > > > related to that? > > > > Yes, and it mostly doesn't work. Lojban's RPN (which, if I have my > > druthers, the next version of the language will not have, by the > > way) is left-recursive, which is problematic. See the peg mailing > > list for various solutions, but IMO since a number of PEG parser > > generators handle this on their own, I think we should just have it > > be left-recursive and say that people have to use such a generator. > > > > If you can figure out how to fix it in in the rules so the right > > behaviour pops out, though, *please* do so. There are links to > > papers on the peg mailing list; it came up just last week; "*[1]* > > *Packrat Parsers Can Support Left Recursion*, Alessandro Warth, > > James R. Douglass, and Todd Millstein (2008)" is the citation I'm > > seeing at a brief glance. > > > > Great. I saw that thread and ignored it as not being relevant in > the moment, but I'm happy to read it and play with it when I get to > that point. > > I've downloaded the paper and cached it with this problem, as I'm a > bit ahead of myself with it. > > -Alan > -- > .i ko djuno fi le do sevzi > > -- > You received this message because you are subscribed to the Google Groups > "lojban" group. > To post to this group, send email to lojban@googlegroups.com. > To unsubscribe from this group, send email to > lojban+unsubscribe@googlegroups.com > . > For more options, visit this group at > http://groups.google.com/group/lojban?hl=en. > > -- You received this message because you are subscribed to the Google Groups "lojban" group. To post to this group, send email to lojban@googlegroups.com. To unsubscribe from this group, send email to lojban+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/lojban?hl=en. --0022150482bb6586b40495c094db Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I've been playing around with the mekso grammar recently. I think I hav= e a rewrite, but I want to finish coding and check that it works as I want = it to. I'll post tomorrow or the day after if people are interested.
mi'e ros

On Wed, Nov 24, 2010 at = 6:01 AM, .alyn.post. <alyn.post@lodockikumazvati.org> wrote:
<= blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; border= -left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
On Tue, Nov 23, 2010 at 10:52:11AM -0800, Robin Lee Powel= l wrote:
> On Tue, Nov 23, 2010 at 11:43:52AM -0700, .alyn.post. wrote:
> > What does the following production in the lojban grammar mean?: > >
> > rp-expression-tail <- rp-expression operator rp-expression-tai= l /
> > ()
> >
> > Do I understand that to mean 'the sequence of rp-expression,<= br> > > operator, and rp-expression-tail OR nothing?' =A0Could the ab= ove
> > also be expressed:
> >
> > rp-expression-tail <- (rp-expression operator rp-expression-ta= il)?
> >
> > And if so, why the odd way of specifying it? =A0I'm weak on p= itfalls
> > of recursive behavior in grammars, am I looking at a workaround > > related to that?
>
> Yes, and it mostly doesn't work. =A0Lojban's RPN (which, if I = have my
> druthers, the next version of the language will not have, by the
> way) is left-recursive, which is problematic. =A0See the peg mailing > list for various solutions, but IMO since a number of PEG parser
> generators handle this on their own, I think we should just have it > be left-recursive and say that people have to use such a generator. >
> If you can figure out how to fix it in in the rules so the right
> behaviour pops out, though, *please* do so. =A0There are links to
> papers on the peg mailing list; it came up just last week; "*[1]*=
> *Packrat Parsers Can Support Left Recursion*, Alessandro Warth,
> James R. Douglass, and Todd Millstein (2008)" is the citation I&#= 39;m
> seeing at a brief glance.
>

Great. =A0I saw that thread and ignored it as not being relevant in the moment, but I'm happy to read it and play with it when I get to
that point.

I've downloaded the paper and cached it with this problem, as I'm a=
bit ahead of myself with it.

-Alan
--
.i ko djuno fi le do sevzi

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