Attempt at recursive map type in OCaml

mapmap.ml

module rec VariantMod
  : sig
    type t = Int of int | Map of t OrderedValMap.t
  end = VariantMod
and OrderedVal
  : sig
    type t = VariantMod.t
    val compare : t -> t -> int
  end
  = struct
    type t = VariantMod.t
    let compare = Pervasives.compare
  end

and OrderedValMap
  : Map.S with type key = OrderedVal.t
  = Map.Make(OrderedVal)

let example_int = VariantMod.Int 42
let example_map_val = OrderedValMap.add example_int example_int OrderedValMap.empty
let example_map = VariantMod.Map example_map_val
let example_map2 = VariantMod.Map (OrderedValMap.add example_map example_map OrderedValMap.empty)