module type PrintableType = sig
  type t
  val pp : out_channel -> t -> unit
  val pplist : out_channel -> t list -> unit
end

module Node : sig
  type t
  val compare : t -> t -> int
  val create : unit -> t
end

module NodeMap : Map.S with type key = Node.t
module NodeSet : Set.S with type elt = Node.t

module type C = sig
  type elt
  type t = {
    empty: bool;
    nodes: NodeSet.t;
    edges: (Node.t * (Node.t option)) NodeMap.t;
    reverseEdges: (Node.t list) NodeMap.t;
    inputVal: elt option;
    outputVal: elt option;
    initial: Node.t option;
    terminal: Node.t option;
    content: elt list NodeMap.t
  }

  val create : unit -> t
  val merge : t -> t -> Node.t -> Node.t -> t
  val concat : t -> t -> t
  val addToLastNode : elt -> t -> t

  val pp : out_channel -> t -> unit
end

module Make (M: PrintableType) : C with type elt = M.t