open Format

type t = int
let make =
  let id = ref ~-1 in
    fun () -> incr id; !id

let compare = (-)

let equal = (==)

external hash : t -> int =  "%identity"

let print fmt x = fprintf fmt "q%a" Pretty.pp_subscript x

let dump fmt x = print fmt x

let check x =
  if x < 0 then failwith (Printf.sprintf "State: Assertion %i < 0 failed" x)

let dummy = max_int