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(* Open Source License                                                       *)
(* Copyright (c) 2023 Nomadic Labs, <contact@nomadic-labs.com>               *)
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(** Abstraction module for OCaml references *)

(** Type [('perm, 'value) t] represents references containing a value
    of type ['value] and permissions specified by ['perm].  *)
type ('perm, 'value) t

(** Read/write reference {!t}. *)
type 'a rw = ([`Read | `Write], 'a) t

(** Read only reference {!t}. *)
type 'a ro = ([`Read], 'a) t

(** [get r] returns the value held by reference [r]. *)
val get : (_, 'a) t -> 'a

(** [set r v] sets reference [r] to the value [v]. *)
val set : 'a rw -> 'a -> unit

(** [map r f] apply [f] to the current value [v] held in the reference
    [r]. *)
val map : ('a -> 'a) -> 'a rw -> unit

(** [new_ v] creates a fresh reference holding value [v]. *)
val new_ : 'a -> (_, 'a) t

(** [readonly r] casts reference [r] to be read only. *)
val readonly : (_, 'a) t -> 'a ro