> On Oct 12, 2017, at 6:31 PM, Alexis King <lexi.lam...@gmail.com> wrote:
> 
>> On Oct 12, 2017, at 1:46 PM, Matthew Flatt <mfl...@cs.utah.edu> wrote:
>> 
>> You could put all the type exports in a submodule. Then, you do need
>> your own variant of `require`, but that variant can mostly just check
>> for the presence of a type submodule, much the way that TR or
>> `plai-typed` do. If the submodule is available, you can import it with
>> the extra scope for types.
> 
> This makes a lot of sense to me, but I’m not completely sure how to
> implement the providing side. I imagine that users may very well want
> to use Racket’s namespace management features with types, leading to
> pathological declarations like this:
> 
>    (provide (except-out (all-from-out foo/bar)
>                         (type-out ExcludedType)))
> 
> If type-out is a provide transformer that doesn’t actually provide
> anything, it merely expands to a submodule (perhaps using
> `syntax-local-lift-module-end-declaration`), then it can’t possibly
> understand that it should be doing something different when used in
> “excluding” position. Is the unfortunate answer here that I can’t get
> around needing to reimplement my own version of `provide` as well?

I just implemented this, and this is a problem, but the `all-from-out` form in 
general is an ever bigger problem, it's completely broken. 

The first strategy is to just lift the provide form into a submodule, but 
`all-from-out` expects there to be a require in the *same* module, 
`all-from-out` always yells at you with the error, all-from-out: no 
corresponding require.

The second strategy is to try to resolve the `all-from-out` references in the 
pre-transformer using `expand-export`. However this is still broken for 
`all-from-out` because `syntax-local-module-required-identifiers` complains 
about "not currently transforming module provides." 
(syntax-local-transforming-module-provides? is false). All-from-out uses 
syntax-local-module-required-identifiers to determine what identifiers should 
be in it, and that needs to be called within a provide-transformer, not a 
provide pre-transformer.

To create a new lifted module I need to use a provide-pre-transformer, but to 
resolve all-from-out's properly I need to use a provide-transformer. Is there 
any way around this?

What I have so far:
https://gist.github.com/AlexKnauth/b7d9f2e0af1c5b8e2186d6581b1f7e4d 
<https://gist.github.com/AlexKnauth/b7d9f2e0af1c5b8e2186d6581b1f7e4d>

Alex Knauth

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