On May 26, 2009, at 14.37 h, Julien Signoles wrote:

My problem here is that I'd like to have a module type T for the functor
Make in b.ml and to avoid the signature duplication in b.mli ... ideally
I'd like to write in b.mli something like :
module type T = sig ???? end
module Make : functor (Extra : A.Extra) -> functor (A : A.T with type extra = Extra.t) -> T with ...
include T with ...
It's clear that I cannot write a module type as follows because the the "open A" will consider the default type of A and not it's
parametrized version ...
module type T = sig
open A
val f : extra -> unit
end
how can I parametrize this signature ? I can write something like :
module type T = functor (A : A.T) ->   sig
   open A
   val f : extra -> unit end ;;
but then I'm a bit lost putting all this together ... I know I'm close ... a small hint ?

Hum, module types cannot be parameterized.

Actually, they can. You just have to put them into a functor. For example:

# module TF (A : sig type t end) =

struct

module type T = sig open A val x : t end

end;;

module TF :

functor (A : sig type t end) -> sig module type T = sig val x : A.t end end

# module I = struct type t = int end;;

module I : sig type t = int end

# module M : TF(I).T = struct let x = 9 end;;

module M : TF(I).T

- Andreas