(*
copyright (c) 2013, simon cruanes
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(** {1 T-Trees}

Shallow, cache-friendly associative data structure.
See {{:http://en.wikipedia.org/wiki/T-tree} wikipedia}.

Not thread-safe.
*)

(** {2 signature} *)

module type S = sig
  type key

  type 'a t

  val empty : 'a t
    (** Empty tree *)

  val add : 'a t -> key -> 'a -> 'a t
    (** Add a binding key/value. If the key already was bound to some
        value, the old binding is erased. *)

  val remove : 'a t -> key -> 'a t
    (** Remove the key *)

  val find : 'a t -> key -> 'a
    (** Find the element associated with this key.
        @raise Not_found if the key is not present *)

  val length : 'a t -> int
    (** Number of bindings *)

  val fold : 'a t -> 'b -> ('b -> key -> 'a -> 'b) -> 'b
    (** Fold on bindings *)
end

(** {2 Functor that builds T trees for comparable keys} *)

module Make(X : Set.OrderedType) : S with type key = X.t