Module type Datatype.Polymorphic2

module type Polymorphic2 = sig .. end
Output signature of Datatype.Polymorphic2.

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