(** Signature for points *)
module type P = sig
  type t

  val empty : t

  val get_coord : t -> Gg.v2

  (** Copy a point and all thoses properties to the given location *)
  val copy : t -> Gg.v2 -> t

end

module type REPR = sig
  type t

  type 'a repr

  (* Start a new path. *)
  val start
    : t -> 'a repr -> 'a repr

  val line_to
    : t -> t -> 'a repr -> 'a repr

  val quadratic_to
    : t -> Gg.v2 -> Gg.v2 -> t -> 'a repr -> 'a repr

  val stop
    : 'a repr -> 'a repr
end

module Make(P:P) : sig

  type t

  (** Create an empty path *)
  val empty: t

  val add_point
    : P.t -> t -> t

  (** Replace the last alement in the path by the one given in parameter *)
  val replace_last
    : P.t -> t -> t

  (** Retrieve the last element, if any *)
  val peek 
    : t -> P.t option

  (** Retrieve the last element, if any *)
  val peek2
    : t -> (P.t * P.t) option

  module Draw(Repr:REPR with type t = P.t) : sig

    (** Represent the the current path *)
    val draw
      : t -> 'a Repr.repr -> 'a Repr.repr
  end

end