module type S = sig
  type t
  val (=) : t -> t -> bool
  val (<>) : t -> t -> bool
  val (<) : t -> t -> bool
  val (<=) : t -> t -> bool
  val (>=) : t -> t -> bool
  val (>) : t -> t -> bool
  val compare : t -> t -> int
  val max : t -> t -> t
  val min : t -> t -> t
end

module Char : S with type t = char
module Bool : S with type t = bool
module Int : S with type t = int
module Int32 : S with type t = int32
module Int64 : S with type t = int64
module Float : S with type t = float
module String : S with type t = string
module List(P : S) : S with type t = P.t list
module Option(P : S) : S with type t = P.t option