Module Datatype.Poly_pair

module Poly_pair: Polymorphic2  with type ('a, 'b) poly = 'a * 'b

include Type.Polymorphic2
module Make: 
functor (T1 : Datatype.S) ->
functor (T2 : Datatype.S) -> Datatype.S with type t = (T1.t, T2.t) poly