type +'a t = int


let nil = ~-1
let null = 0
let is_nil x = x == ~-1
let print fmt = Format.fprintf fmt "%i"

let equal (x : 'a t) (y : 'a t) = x == y
external ibool : bool -> int = "%identity"
let compare (x : 'a t) (y : 'a t) = ibool (y > x) - ibool (y < x)
let hash (x : 'a t) = x land 0x7fffffff

external to_int : 'a t -> int = "%identity"
external of_int : int -> 'a t = "%identity"