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From: Thomas Gazagnaire <thomas.gazagnaire@irisa.fr>
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Problem with precedence declaration in .mly file
Date: Wed, 31 Oct 2007 15:14:59 +0100	[thread overview]
Message-ID: <47288DE3.3000603@irisa.fr> (raw)
In-Reply-To: <21DAF2E3-1E29-476D-BEB3-FD608EBD92A2@cs.rice.edu>

The following code works perfectly for me. Maybe you introduce some 
undesired precedence rules in your grammar rules.


----

%token <int> INT
%token PLUS MINUS DIVIDE STAR ATOB END

%start main
%type <int> main

%left PLUS MINUS
%left STAR DIVIDE
%left ATOB

%%


main:
| expr END { $1 }

expr:
| INT { $1 }
| expr PLUS expr { $1 + $3 }
| expr MINUS expr { $1 - $3 }
| expr DIVIDE expr { $1 / $3 }
| expr STAR expr { $1 * $3 }
| expr ATOB expr { int_of_float ( (float_of_int $1) ** (float_of_int $3) ) }
;

---

And then "2^2+7\n" gives me "11"

Cheers,
Thomas

Angela Zhu a écrit :
> 
> On Oct 31, 2007, at 6:52 AM, Peter Ilberg wrote:
> 
>>
>> I have no experience with ocamlyacc, but looking at your grammar 
>> below, it seems that you don't need the 'value PLUS exp' etc rules. 
>> All these cases should be covered already by the 'exp PLUS exp' rules 
>> at the beginning and the 'value' rule at the end.
>>
>> Try removing the 'value PLUS exp' rules. Maybe ocamlyacc gets confused 
>> if it has two sets of productions that it has to disambiguate with 
>> precedence rules.
> 
> I removed 'value PLUS exp' rules.
> The precedence is still not correct, what is more, 1+ t (with t 
> declared) gives a syntax error.
> 
> Thanks,
> Angela
> 
> 
> 
>>
>> --- Peter
> 
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  reply	other threads:[~2007-10-31 14:14 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
     [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 [this message]
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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