Re: [Caml-list] Problems building a library, types go missing

[Goswin von Brederlow <goswin-v-b@web.de>]

On Mon, Jul 29, 2013 at 12:03:33PM +0100, Leo White wrote:
> 
> If you look at the interfaces for works.ml and fails.ml (using "ocamlc
> -i"), you can see the problem:
> 
> works.ml:
> 
>   module Foo : sig module T : sig type t = int val foo : t -> unit end end
>   module Functor :
>     sig
>       module type Foo_t = sig type t val foo : t -> unit end
>       module Make : functor (Foo : Foo_t) -> sig val do_foo : Foo.t -> unit end
>     end
> 
> fails.ml:
> 
>   module Foo : sig module T : sig type t = int val foo : t -> unit end end
>   module Foo_t : sig module type T_t = sig type t val foo : t -> unit end end
>   module Functor :
>     sig
>       module Make :
>         functor (Foo : IntFoo_t.T_t) -> sig val do_foo : Foo.t -> unit end
>     end
> 
> As you can see the Fails.Functor.Make functor expects an argument with
> module type IntFoo_t.T_t, while the Works.Functor.Make functor expects
> an argument with module type Works.Functor.Foo_t.
> 
> Since you hide IntFoo_t when compiling your tests, the compiler cannot
> find IntFoo_t.T_t and so it cannot check whether Fails.Functor.Make is
> being applied correctly.
>
> To fix this simply add a signature to Fails.Functor, or better yet add a 
> "fails.mli" to your project:
> 
>   module Foo : sig module T : sig type t = int val foo : t -> unit end end
>   module Foo_t : sig module type T_t = sig type t val foo : t -> unit end end
>   module Functor :
>     sig
>       module Make :
>         functor (Foo : Foo_t.T_t) -> sig val do_foo : Foo.t -> unit end
>     end
> 
> Regards,
> 
> Leo

Can I use some "with type" syntax instead? Something like

module Functor = (IntFails with type IntFoo_t.T_t = Foo_t.T_t)

I'm trying to keep the files short and few so I don't have to edit
multiple files every time I change something. At least till the API
stabilizes.

MfG
	Goswin