Re: [Caml-list] Limitations on $n in ocamlyacc?

[John Skaller <skaller@users.sourceforge.net>]

On Fri, 2005-05-27 at 10:24 +0200, Alex Baretta wrote:
> What is the limit on the number of token values accessible with the $n
> notation in ocamlyacc semantic actions? I'm asking because I'm
> consistently getting ocamlyacc errors like the following, which I can't
> make sense of.
> 
> ocamlyacc: e - line 96 of "xcaml_dictionary_yacc.mly", $5 is unbound

This is because the symbol has no argument:

%token FRED
p: FRED { $1 } 

will give this error, but

%token<int> JOE

q: JOE { $1 } 

makes non-terminal q of type int, the type of JOE's argument.

It is equivalent to:

type token = 
 | FRED
 | JOE of int

then

match (x:token) with 
| FRED ?a -> .. (* ERROR -- FRED is a constant constructor *)
| JOE ?a -> .. (* OK -- JOE is a nonconstant constructor *)

-- 
John Skaller, skaller at users.sf.net
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