[Caml-list] module alias in a .mli file

[Caml-list] module alias in a .mli file

[Francois Berenger]

Hello,

Here is my stupid question of the day:
can't I declare the following in a .mli file?

module V3 = Vector3

Thanks a lot,
F.

Re: [Caml-list] module alias in a .mli file

[Martin Jambon]

On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
> Hello,
>
> Here is my stupid question of the day:
> can't I declare the following in a .mli file?
>
> module V3 = Vector3

No, because "= Vector3" specifies an implementation.
An mli file is a module interface, and module interfaces never contain 
implementations.

However, you may want to do this, which does what it says:

  module V3 : module type of Vector3

("language extension", since ocaml 3.12)


Martin

Re: [Caml-list] module alias in a .mli file

[Francois Berenger]

On 11/19/2012 03:02 PM, Martin Jambon wrote:
> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
>> Hello,
>>
>> Here is my stupid question of the day:
>> can't I declare the following in a .mli file?
>>
>> module V3 = Vector3
>
> No, because "= Vector3" specifies an implementation.
> An mli file is a module interface, and module interfaces never contain
> implementations.
>
> However, you may want to do this, which does what it says:
>
>   module V3 : module type of Vector3

Thanks a lot! That's exactly what I needed. :)

Re: [Caml-list] module alias in a .mli file

[David House]

Annoyingly though, there is no way to create a module alias in an mli.

If, in an ml file, you have to refer often to
Some_very_long_module_name, it can quite convenient to define an alias
by doing "module Mod = Some_very_long_module_name" (or, locally, "let
module Mod = Some_very_long_module_name in"). But there is no way of
doing this in an mli: you have to use the long name every time.

This is especially annoying if you have some big type that you want to
expose in the mli. You really just want to copy-paste out of the ml
file and stick it into the mli, but then you have to expand all the
module aliases. (It's just a couple of goes with M-%, but still...)

On Mon, Nov 19, 2012 at 6:36 AM, Francois Berenger <berenger@riken.jp> wrote:
> On 11/19/2012 03:02 PM, Martin Jambon wrote:
>>
>> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
>>>
>>> Hello,
>>>
>>> Here is my stupid question of the day:
>>> can't I declare the following in a .mli file?
>>>
>>> module V3 = Vector3
>>
>>
>> No, because "= Vector3" specifies an implementation.
>> An mli file is a module interface, and module interfaces never contain
>> implementations.
>>
>> However, you may want to do this, which does what it says:
>>
>>   module V3 : module type of Vector3
>
>
> Thanks a lot! That's exactly what I needed. :)
>
>
>
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs

Re: [Caml-list] module alias in a .mli file

[Paolo Donadeo]

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Actually this is not true, Martin explained how. :-)


-- 
Paolo
Sent by Gmail from Android
Il giorno 19/nov/2012 11:35, "David House" <dhouse@janestreet.com> ha
scritto:

> Annoyingly though, there is no way to create a module alias in an mli.
>
> If, in an ml file, you have to refer often to
> Some_very_long_module_name, it can quite convenient to define an alias
> by doing "module Mod = Some_very_long_module_name" (or, locally, "let
> module Mod = Some_very_long_module_name in"). But there is no way of
> doing this in an mli: you have to use the long name every time.
>
> This is especially annoying if you have some big type that you want to
> expose in the mli. You really just want to copy-paste out of the ml
> file and stick it into the mli, but then you have to expand all the
> module aliases. (It's just a couple of goes with M-%, but still...)
>
> On Mon, Nov 19, 2012 at 6:36 AM, Francois Berenger <berenger@riken.jp>
> wrote:
> > On 11/19/2012 03:02 PM, Martin Jambon wrote:
> >>
> >> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
> >>>
> >>> Hello,
> >>>
> >>> Here is my stupid question of the day:
> >>> can't I declare the following in a .mli file?
> >>>
> >>> module V3 = Vector3
> >>
> >>
> >> No, because "= Vector3" specifies an implementation.
> >> An mli file is a module interface, and module interfaces never contain
> >> implementations.
> >>
> >> However, you may want to do this, which does what it says:
> >>
> >>   module V3 : module type of Vector3
> >
> >
> > Thanks a lot! That's exactly what I needed. :)
> >
> >
> >
> >
> > --
> > Caml-list mailing list.  Subscription management and archives:
> > https://sympa.inria.fr/sympa/arc/caml-list
> > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> > Bug reports: http://caml.inria.fr/bin/caml-bugs
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>

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Re: [Caml-list] module alias in a .mli file

[Tiphaine Turpin]

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In fact, the solution

  module V3 : module type of Vector3

does not work completely, because, the equality between Vector3 and V3
is lost, which poses problem with the types defined by Vector 3. What
works is:

  include module type of struct module V3 = Vector3 end

Here is a full example:

module M : sig

  module Vector3 : sig type t end
  (* module V3 : module type of Vector3 *)
  include module type of struct module V3 = Vector3 end

end = struct

  module Vector3 = struct type t end
  module V3 = Vector3

end 

open M
let id (x : Vector3.t) : V3.t = x


Regards,

Tiphaine


On 11/19/12 13:44, Paolo Donadeo wrote:
>
> Actually this is not true, Martin explained how. :-)
>
>
> -- 
> Paolo
> Sent by Gmail from Android
>
> Il giorno 19/nov/2012 11:35, "David House" <dhouse@janestreet.com
> <mailto:dhouse@janestreet.com>> ha scritto:
>
>     Annoyingly though, there is no way to create a module alias in an mli.
>
>     If, in an ml file, you have to refer often to
>     Some_very_long_module_name, it can quite convenient to define an alias
>     by doing "module Mod = Some_very_long_module_name" (or, locally, "let
>     module Mod = Some_very_long_module_name in"). But there is no way of
>     doing this in an mli: you have to use the long name every time.
>
>     This is especially annoying if you have some big type that you want to
>     expose in the mli. You really just want to copy-paste out of the ml
>     file and stick it into the mli, but then you have to expand all the
>     module aliases. (It's just a couple of goes with M-%, but still...)
>
>     On Mon, Nov 19, 2012 at 6:36 AM, Francois Berenger
>     <berenger@riken.jp <mailto:berenger@riken.jp>> wrote:
>     > On 11/19/2012 03:02 PM, Martin Jambon wrote:
>     >>
>     >> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
>     >>>
>     >>> Hello,
>     >>>
>     >>> Here is my stupid question of the day:
>     >>> can't I declare the following in a .mli file?
>     >>>
>     >>> module V3 = Vector3
>     >>
>     >>
>     >> No, because "= Vector3" specifies an implementation.
>     >> An mli file is a module interface, and module interfaces never
>     contain
>     >> implementations.
>     >>
>     >> However, you may want to do this, which does what it says:
>     >>
>     >>   module V3 : module type of Vector3
>     >
>     >
>     > Thanks a lot! That's exactly what I needed. :)
>     >
>     >
>     >
>     >
>     > --
>     > Caml-list mailing list.  Subscription management and archives:
>     > https://sympa.inria.fr/sympa/arc/caml-list
>     > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>     > Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>     --
>     Caml-list mailing list.  Subscription management and archives:
>     https://sympa.inria.fr/sympa/arc/caml-list
>     Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>     Bug reports: http://caml.inria.fr/bin/caml-bugs
>


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Re: [Caml-list] module alias in a .mli file

[David House]

Very clever! I had always been doing the following to re-establish the
type equality:

  module V3 : module type of Vector3
    with type t = Vector3.t
    with type Submodule.t = Vector3.Submodule.t
    ... etc

But again: this is not a true alias. It actually defines and exposes a
V3 module as a submodule of your module. E.g. if you're talking about
foo.mli then other people would be able to say Foo.V3.

On Mon, Nov 19, 2012 at 3:46 PM, Tiphaine Turpin
<Tiphaine.Turpin@free.fr> wrote:
> In fact, the solution
>
>
>   module V3 : module type of Vector3
>
> does not work completely, because, the equality between Vector3 and V3 is
> lost, which poses problem with the types defined by Vector 3. What works is:
>
>   include module type of struct module V3 = Vector3 end
>
> Here is a full example:
>
> module M : sig
>
>   module Vector3 : sig type t end
>   (* module V3 : module type of Vector3 *)
>   include module type of struct module V3 = Vector3 end
>
> end = struct
>
>   module Vector3 = struct type t end
>   module V3 = Vector3
>
> end
>
> open M
> let id (x : Vector3.t) : V3.t = x
>
>
> Regards,
>
> Tiphaine
>
>
>
> On 11/19/12 13:44, Paolo Donadeo wrote:
>
> Actually this is not true, Martin explained how. :-)
>
>
> --
> Paolo
> Sent by Gmail from Android
>
> Il giorno 19/nov/2012 11:35, "David House" <dhouse@janestreet.com> ha
> scritto:
>>
>> Annoyingly though, there is no way to create a module alias in an mli.
>>
>> If, in an ml file, you have to refer often to
>> Some_very_long_module_name, it can quite convenient to define an alias
>> by doing "module Mod = Some_very_long_module_name" (or, locally, "let
>> module Mod = Some_very_long_module_name in"). But there is no way of
>> doing this in an mli: you have to use the long name every time.
>>
>> This is especially annoying if you have some big type that you want to
>> expose in the mli. You really just want to copy-paste out of the ml
>> file and stick it into the mli, but then you have to expand all the
>> module aliases. (It's just a couple of goes with M-%, but still...)
>>
>> On Mon, Nov 19, 2012 at 6:36 AM, Francois Berenger <berenger@riken.jp>
>> wrote:
>> > On 11/19/2012 03:02 PM, Martin Jambon wrote:
>> >>
>> >> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
>> >>>
>> >>> Hello,
>> >>>
>> >>> Here is my stupid question of the day:
>> >>> can't I declare the following in a .mli file?
>> >>>
>> >>> module V3 = Vector3
>> >>
>> >>
>> >> No, because "= Vector3" specifies an implementation.
>> >> An mli file is a module interface, and module interfaces never contain
>> >> implementations.
>> >>
>> >> However, you may want to do this, which does what it says:
>> >>
>> >>   module V3 : module type of Vector3
>> >
>> >
>> > Thanks a lot! That's exactly what I needed. :)
>> >
>> >
>> >
>> >
>> > --
>> > Caml-list mailing list.  Subscription management and archives:
>> > https://sympa.inria.fr/sympa/arc/caml-list
>> > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>> > Bug reports: http://caml.inria.fr/bin/caml-bugs
>>
>> --
>> Caml-list mailing list.  Subscription management and archives:
>> https://sympa.inria.fr/sympa/arc/caml-list
>> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>

Re: [Caml-list] module alias in a .mli file

[Francois Berenger]

On 11/20/2012 12:46 AM, Tiphaine Turpin wrote:
> In fact, the solution
>
>    module V3 : module type of Vector3
>
> does not work completely, because, the equality between Vector3 and V3
> is lost, which poses problem with the types defined by Vector 3. What
> works is:
>
>    include module type of struct module V3 = Vector3 end

It's a little verbose but might be closer to what I was looking for.

> Here is a full example:
>
> module M : sig
>
>    module Vector3 : sig type t end
>    (* module V3 : module type of Vector3 *)
>    include module type of struct module V3 = Vector3 end
>
> end = struct
>
>    module Vector3 = struct type t end
>    module V3 = Vector3
>
> end
>
> open M
> let id (x : Vector3.t) : V3.t = x
>
>
> Regards,
>
> Tiphaine
>
>
> On 11/19/12 13:44, Paolo Donadeo wrote:
>>
>> Actually this is not true, Martin explained how. :-)
>>
>>
>> --
>> Paolo
>> Sent by Gmail from Android
>>
>> Il giorno 19/nov/2012 11:35, "David House" <dhouse@janestreet.com
>> <mailto:dhouse@janestreet.com>> ha scritto:
>>
>>     Annoyingly though, there is no way to create a module alias in an mli.
>>
>>     If, in an ml file, you have to refer often to
>>     Some_very_long_module_name, it can quite convenient to define an alias
>>     by doing "module Mod = Some_very_long_module_name" (or, locally, "let
>>     module Mod = Some_very_long_module_name in"). But there is no way of
>>     doing this in an mli: you have to use the long name every time.
>>
>>     This is especially annoying if you have some big type that you want to
>>     expose in the mli. You really just want to copy-paste out of the ml
>>     file and stick it into the mli, but then you have to expand all the
>>     module aliases. (It's just a couple of goes with M-%, but still...)
>>
>>     On Mon, Nov 19, 2012 at 6:36 AM, Francois Berenger
>>     <berenger@riken.jp <mailto:berenger@riken.jp>> wrote:
>>     > On 11/19/2012 03:02 PM, Martin Jambon wrote:
>>     >>
>>     >> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
>>     >>>
>>     >>> Hello,
>>     >>>
>>     >>> Here is my stupid question of the day:
>>     >>> can't I declare the following in a .mli file?
>>     >>>
>>     >>> module V3 = Vector3
>>     >>
>>     >>
>>     >> No, because "= Vector3" specifies an implementation.
>>     >> An mli file is a module interface, and module interfaces never
>>     contain
>>     >> implementations.
>>     >>
>>     >> However, you may want to do this, which does what it says:
>>     >>
>>     >>   module V3 : module type of Vector3
>>     >
>>     >
>>     > Thanks a lot! That's exactly what I needed. :)
>>     >
>>     >
>>     >
>>     >
>>     > --
>>     > Caml-list mailing list.  Subscription management and archives:
>>     > https://sympa.inria.fr/sympa/arc/caml-list
>>     > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>>     > Bug reports: http://caml.inria.fr/bin/caml-bugs
>>
>>     --
>>     Caml-list mailing list.  Subscription management and archives:
>>     https://sympa.inria.fr/sympa/arc/caml-list
>>     Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>>     Bug reports: http://caml.inria.fr/bin/caml-bugs
>>
>

Re: [Caml-list] module alias in a .mli file

[Francois Berenger]

On 11/20/2012 10:38 AM, Francois Berenger wrote:
> On 11/20/2012 12:46 AM, Tiphaine Turpin wrote:
>> In fact, the solution
>>
>>    module V3 : module type of Vector3
>>
>> does not work completely, because, the equality between Vector3 and V3
>> is lost, which poses problem with the types defined by Vector 3. What
>> works is:
>>
>>    include module type of struct module V3 = Vector3 end
>
> It's a little verbose but might be closer to what I was looking for.

Indeed, now I can write (and compile) a .mli file with:

---
include module type of struct module BA  = Bigarray        end
include module type of struct module BA3 = Bigarray.Array3 end
[...]
mutable grid : (int, BA.int8_unsigned_elt, BA.c_layout) BA3.t
[...]
---

Which is more compact than what I had previously.

Thanks! :)
F.

>> Here is a full example:
>>
>> module M : sig
>>
>>    module Vector3 : sig type t end
>>    (* module V3 : module type of Vector3 *)
>>    include module type of struct module V3 = Vector3 end
>>
>> end = struct
>>
>>    module Vector3 = struct type t end
>>    module V3 = Vector3
>>
>> end
>>
>> open M
>> let id (x : Vector3.t) : V3.t = x
>>
>>
>> Regards,
>>
>> Tiphaine
>>
>>
>> On 11/19/12 13:44, Paolo Donadeo wrote:
>>>
>>> Actually this is not true, Martin explained how. :-)
>>>
>>>
>>> --
>>> Paolo
>>> Sent by Gmail from Android
>>>
>>> Il giorno 19/nov/2012 11:35, "David House" <dhouse@janestreet.com
>>> <mailto:dhouse@janestreet.com>> ha scritto:
>>>
>>>     Annoyingly though, there is no way to create a module alias in an
>>> mli.
>>>
>>>     If, in an ml file, you have to refer often to
>>>     Some_very_long_module_name, it can quite convenient to define an
>>> alias
>>>     by doing "module Mod = Some_very_long_module_name" (or, locally,
>>> "let
>>>     module Mod = Some_very_long_module_name in"). But there is no way of
>>>     doing this in an mli: you have to use the long name every time.
>>>
>>>     This is especially annoying if you have some big type that you
>>> want to
>>>     expose in the mli. You really just want to copy-paste out of the ml
>>>     file and stick it into the mli, but then you have to expand all the
>>>     module aliases. (It's just a couple of goes with M-%, but still...)
>>>
>>>     On Mon, Nov 19, 2012 at 6:36 AM, Francois Berenger
>>>     <berenger@riken.jp <mailto:berenger@riken.jp>> wrote:
>>>     > On 11/19/2012 03:02 PM, Martin Jambon wrote:
>>>     >>
>>>     >> On Sun 18 Nov 2012 09:29:31 PM PST, Francois Berenger wrote:
>>>     >>>
>>>     >>> Hello,
>>>     >>>
>>>     >>> Here is my stupid question of the day:
>>>     >>> can't I declare the following in a .mli file?
>>>     >>>
>>>     >>> module V3 = Vector3
>>>     >>
>>>     >>
>>>     >> No, because "= Vector3" specifies an implementation.
>>>     >> An mli file is a module interface, and module interfaces never
>>>     contain
>>>     >> implementations.
>>>     >>
>>>     >> However, you may want to do this, which does what it says:
>>>     >>
>>>     >>   module V3 : module type of Vector3
>>>     >
>>>     >
>>>     > Thanks a lot! That's exactly what I needed. :)
>>>     >
>>>     >
>>>     >
>>>     >
>>>     > --
>>>     > Caml-list mailing list.  Subscription management and archives:
>>>     > https://sympa.inria.fr/sympa/arc/caml-list
>>>     > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>>>     > Bug reports: http://caml.inria.fr/bin/caml-bugs
>>>
>>>     --
>>>     Caml-list mailing list.  Subscription management and archives:
>>>     https://sympa.inria.fr/sympa/arc/caml-list
>>>     Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>>>     Bug reports: http://caml.inria.fr/bin/caml-bugs
>>>
>>
>
>

Re: [Caml-list] module alias in a .mli file

[Wojciech Meyer]

module V3 : module type of Vector3

Francois Berenger <berenger@riken.jp> writes:

> Hello,
>
> Here is my stupid question of the day:
> can't I declare the following in a .mli file?
>
> module V3 = Vector3
>
> Thanks a lot,
> F.

--
Wojciech Meyer
http://danmey.org