showable.ml

module type showable = sig
  type t
  val show: t -> string
end

(** Typeclass emulation *)
let show (type a) (module M: showable with type t = a) x = M.show x

(** Or with a type abbreviation *)
type 'a showable = (module showable with type t = 'a)
let show (type a) ((module M):a showable) x = M.show x