(*THIS WORKS*)
module type Comparable = sig
  type t

  val compare : t -> t -> int
end

module  Comparable = struct
  type t = string

  let compare = String.compare

end

module M = Map.Make(Comparable)





(*THIS DOES NOT WORK ->>*)

module type Comparable = sig
  type t

  val compare : t -> t -> int
end

module M = Map.Make(T : Comparable)