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[Caml-list] infix precedence
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Date: | 2002-05-28 (22:44) |
From: | Daniel de Rauglaudre <daniel.de_rauglaudre@i...> |
Subject: | Re: [Caml-list] infix precedence |
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/ ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners