(*
Copyright (c) 2013, Simon Cruanes
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*)

(** {1 Universal type} *)

(** This is largely inspired by https://ocaml.janestreet.com/?q=node/18 . *)

type t
  (** The universal type *)

type 'a embedding = {
  pack : 'a -> t;           (** Pack a 'a into a univ value *)
  unpack : t -> 'a option;  (** Try to unpack the univ value into an 'a *)
  set : t -> 'a -> unit;    (** Change, in-place, the content of the univ value *)
  compatible : t -> bool;   (** Check whether the univ value can be unpacked *)
} (** Conversion between the universal type and 'a *)

val embed : unit -> 'a embedding
  (** Create a new embedding. Values packed by a given embedding can
      only be unpacked by the same embedding. *)