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(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* The OCaml programmers *)
(* *)
(* Copyright 2022 Institut National de Recherche en Informatique et *)
(* en Automatique. *)
(* *)
(* All rights reserved. This file is distributed under the terms of *)
(* the GNU Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
(* Type equality witness *)
type (_, _) eq = Equal: ('a, 'a) eq
(* Type identifiers *)
module Id = struct
type _ id = ..
module type ID = sig
type t
type _ id += Id : t id
end
type !'a t = (module ID with type t = 'a)
let make (type a) () : a t =
(module struct type t = a type _ id += Id : t id end)
let[@inline] uid (type a) ((module A) : a t) =
Obj.Extension_constructor.id (Obj.Extension_constructor.of_val A.Id)
let provably_equal
(type a b) ((module A) : a t) ((module B) : b t) : (a, b) eq option
=
match A.Id with B.Id -> Some Equal | _ -> None
end
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