Quick Non Extensible Example

Deprecation Warning: this tutorial describes technology that is considered obsolete. It's been replaced by extensions points and ppx rewriters

quick_non_extensible_example.ml

(* This scheme only works when the grammar value is not really
   used for other things than entry creation. In fact grammars
   are now static by default. *)
type t1 = A | B
type t2 = Foo of string * t1
open Camlp4.PreCast
open Syntax
let foo = Gram.Entry.mk "foo"
let bar = Gram.Entry.mk "bar"
let () =
  EXTEND Gram
    GLOBAL: foo bar;
    foo: [ [ "foo"; i = LIDENT; b = bar -> Foo(i, b) ] ];
    bar: [ [ "?" -> A | "." -> B ] ];
  END;;
Gram.parse_string foo (Loc.mk "<string>") "foo x?" = Foo("x", A);;
DELETE_RULE Gram foo: "foo"; LIDENT; bar END