Re: [Caml-list] RFH: Values do not match: val bar1 : Foo.foo_t is not included in val bar1 : Foo.foo_t

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

Julien Signoles <julien.signoles@gmail.com> writes:

> Hello,
>
> 2010/5/24 Goswin von Brederlow <goswin-v-b@web.de>
>
>     I'm playing around with packs and ways to avoid having to duplicate
>     module signatures all over the place. So I came up with the following
>     idea: Each module declares an external and internal module type and
>     restricts itself to the internal type. The pack then further restricts
>     the module to the external type.
>
>     But then I get a type error I can't make heads or tails of: 
>
>
>     File "pack.cmx", line 1, characters 0-1:
>     Error: The implementation (obtained by packing)
>           does not match the interface pack.mli:
>           Modules do not match:
>             sig
>               module type Extern = sig val bar1 : Foo.foo_t end
>               module type Intern =
>                 sig val bar1 : Foo.foo_t val bar2 : Foo.foo_t end
>               module I : sig val bar1 : Foo.foo_t val bar2 : Foo.foo_t end
>               val bar1 : Foo.foo_t
>               val bar2 : Foo.foo_t
>             end
>           is not included in
>             sig val bar1 : Foo.foo_t end
>           Values do not match:
>             val bar1 : Foo.foo_t
>           is not included in
>             val bar1 : Foo.foo_t
>     make: *** [all] Error 2 
>
>
>
>     Can anyone explain that to me?
>
>
> The error message is not very helpful here. But don't refer to an internal
> generative type (namely Foo.foo_t) in your packing signature pack.mli. To solve
> your issue, you have to declare the type foo_t outside the pack like I said in
> a previous message (http://caml.inria.fr/pub/ml-archives/caml-list/2010/05/
> b79d812d9dfb99e12c8e924f83d7168c.en.html).
>
> Hope this helps,
> Julien

That sounds like a bug then.

I was trying hard not to repeat information in different places. That
just ends up with one of them getting out of sync.

MfG
        Goswin