[ocaml-platform] Changes to my previous proposal for namespaces

[Yaron Minsky]

This proposal makes me happy.

y
On Mar 15, 2013 9:43 AM, "Leo White" <lpw25 at cam.ac.uk> wrote:

> Following recent discussions, I would like to propose some changes to my
> previous proposal:
>
> ## Flat namespaces
>
> It has occured to me that, while I have some good use cases for
> hierarchical namespaces, they are not critical for the *initial*
> implementation of namespaces in OCaml. Essentially, I'm changing my
> position from "We should include support for hierarchical namespaces" to
> "We should make sure that we could easily add support for hierarchical
> namespaces in the future".
>
> ## Pervasive modules
>
> I think that the simplest solution to Yaron's need for "automatically
> opened" modules is to say that:
>
>     open namespace Foo
>
> will open the namespace Foo and then, if it exists, open the module
> Foo#Pervasives.
>
> Members of Foo#Pervasives would not be accessible directly from Foo
> (i.e. Foo#id != Foo#Pervasives.id).
>
> I think this has the following benefits:
>
> - This is basically a syntactic solution: we don't need to "dirty" the
>   semantics or specification of modules with the issue of automatically
>   opening modules.
>
> - Only one Pervasives is opened, so conflicts between separate
>   specifications of a namespace should be obvious immediately. Its
>   relience on a specific name also makes the potential for conflicts
>   obvious to users.
>
> - It is clearly a bit of a fudge, which will discourage its excessive
>   use, and prevent any percevied overlap bewteen namespaces and
>   modules. This also makes it seem less "offensive" that it slightly
>   breaks the idea that "let open namespace Foo in id" should be
>   basically the same as "Foo#id"
>
> - It fits in with the standard library's use of Pervasives. You could
>   consider current behaviour as simply opening the "Std" namespace
>   before every program.
>
> I think that simple solution is better than trying to find a generalised
> sematics for "automatic opens" in namespaces. As Gabriel's e-mail shows,
> these semantics are non-trivial. I think that it is better to solve a
> specific problem with a specific solution, rather than creating a
> generalised solution for its own sake.
>
> Regards,
>
> Leo
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