From: skaller <skaller@users.sourceforge.net>
To: Angela Zhu <angela.zhu@cs.rice.edu>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Problem with precedence declaration in .mly file
Date: Wed, 31 Oct 2007 16:52:00 +1100 [thread overview]
Message-ID: <1193809920.8355.41.camel@rosella.wigram> (raw)
In-Reply-To: <23EC0ABA-12EE-49DE-B76A-1D91BCCAE1BA@cs.rice.edu>
On Tue, 2007-10-30 at 23:26 -0500, Angela Zhu wrote:
> /***** Precedence Rules *****/
> ...
> %left PLUS MINUS
> %left STAR DIVIDE
> %left ATOB
> Can any one help me to see why it happens? Why the precedence rules
> doesn't work?
> Precedences also can be created by sophisticated
> organization of the grammar rules.
> But I want to avoid this.
DO NOT USE THEM. The rules are hard to explain and very badly
designed, in other words, they're a hack. Ocaml provides
them for compatibility with older yacc like tools.
Write your grammar properly instead, in pseudo code:
term = factor | term + factor
factor = atom | factor * atom
atom = INTEGER | ( term )
gives the precedence of * over + and left associativity,
without using incomprehensible precedence rules.
--
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
next prev parent reply other threads:[~2007-10-31 5:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-30 14:00 Angela Zhu
2007-10-30 14:20 ` [Caml-list] " Oliver Bandel
[not found] ` <1193753915.47273d3bb15f2@webmail.in-berlin.de>
2007-10-31 4:11 ` Angela Zhu
2007-10-31 4:26 ` Angela Zhu
2007-10-31 5:52 ` skaller [this message]
[not found] ` <BE3BA36D-7E69-426F-B558-26CBCF9D78F6@cs.rice.edu>
[not found] ` <1193814307.8355.68.camel@rosella.wigram>
2007-10-31 7:16 ` Re: " Angela Zhu
2007-10-31 11:52 ` Peter Ilberg
2007-10-31 13:51 ` Angela Zhu
2007-10-31 14:14 ` Thomas Gazagnaire
2007-10-31 14:40 ` Angela Zhu
[not found] ` <472894EC.8040902@irisa.fr>
[not found] ` <F5672A31-E4C0-488B-B594-F75E3DA262D8@cs.rice.edu>
[not found] ` <47289C47.8020609@irisa.fr>
2007-10-31 15:34 ` Angela Zhu
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