Re: [Caml-list] infix precedence

[dengping zhu <zhudp@cs.bu.edu>]

Hi, Daniel, it works very well.
Thanks a lot!

Dengping




On Wed, 29 May 2002, Daniel de Rauglaudre wrote:

>Hi,
>
>On Tue, May 28, 2002 at 02:48:42PM -0400, dengping zhu wrote:
>> 
>> I tried camlp4 before. I got the example from the camlp4 tutorial and
>> modified a little bit. 
>
>Your code cannot work: you are defining a new entry, you are not using
>the entry of OCaml expressions, which is Pcaml.expr.
>
>  $ cat foo.ml
>  let add_infix lev op =
>  EXTEND
>    GLOBAL: Pcaml.expr;
>    Pcaml.expr: LEVEL $lev$
>      [ [ x = SELF; $op$; y = SELF -> <:expr< $lid:op$ $x$ $y$ >> ] ];
>  END;;
>  $ ocaml
>	  Objective Caml version 3.04+11 (2002-05-16)
>  
>  # #load "camlp4o.cma";;
>	  Camlp4s Parsing version 3.04+11
>  
>  # #load "pa_extend.cmo";;    
>  # #load "q_MLast.cmo";;  
>  # #use "foo.ml";;
>  val add_infix : string -> string -> unit = <fun>
>
>Type:
>   Grammar.Entry.print Pcaml.expr;;
>to see the current entry of expressions.
>
>The available levels are "top", "expr1", ":=", "||", "&&", "<", "^",
>"+", "*", "**", "unary minus", "apply", "label", ".", "~-", "simple".
>They are the one you can use as first parameter of add_infix:
>
>  # add_infix "*" "op1";;
>
>If you type
>   Grammar.Entry.print Pcaml.expr;;
>then you see that the rule with "op1" has been added in the level "*".
>
>  # let op1 x y = x + y + 1;;
>  Toplevel input:
>  # let op1 x y = x + y + 1;;
>	^^^
>  Parse error: 'module' uppercase identifier expected after 'let' (in
>    [str_item])
>
>Normal, since "op1" is now a keyword. Mmmm... the normal form should be:
>   let (op1) x y = x + y + 1;;
>But it does not work... this is a bug in Camlp4 that I am going to fix.
>
>A solution should be to define it before the "add_infix"...
>
>But, in the meantime, this works:
>   # let \op1 x y = x + y + 1;;
>   val op1 : int -> int -> int = <fun>
>   # 3 op1 4;;
>   - : int = 8
>
>-- 
>Daniel de RAUGLAUDRE
>daniel.de_rauglaudre@inria.fr
>http://cristal.inria.fr/~ddr/
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