Try to implement Haskell's show in OCaml using ppx_overload

show.ml

module type Show = sig
  val show : 'a -> string
end

module Show = struct
  external show : 'a -> string = "%OVERLOADED"

  module Int = struct
    let show = string_of_int
  end

  module Float = struct
    let show = string_of_float
  end

  (* too ambiguous *)
  module Tuple2 = struct
    let show (a, b) = show a ^ ", " ^ show b
  end

  (* functor? *)
  module Tuple2 (A : Show) (B : Show) = struct
    let show (a, b) = A.show a ^ ", " ^ B.show b
  end
end

Why not use english:(