The way this works, the box doesn't have to "get into" any modules
that aren't typed. Instead, when expanding a module A, that module
may contain uses of identifiers defined in a typed module T. Those
identifiers are macros that look something like this:
(define-syntax (id stx) (if typed-context? #'typed-id #'id-for-untyped))
Furthermore, the typed-context? value is initially set to #f, and it's
set to #true only inside the typechecker. When `id` is used in an
untyped module, it never gets set to #true, and so the
`id-for-untyped` is used. That means that the untyped code doesn't
need to know or do anything to make the system work, which is
necessary for Typed Racket to be a library.
There's more detail about this in our Scheme Workshop paper, here:
https://www2.ccs.neu.edu/racket/pubs/scheme2007-ctf.pdf
Sam
On Wed, Oct 7, 2020 at 6:18 AM Nate Griswold <nategrisw...@gmail.com> wrote:
>
> I just finished reading the paper "Languages as Libraries", which really
> helped as an introduction to racket's language system (i had previously been
> ignoring the syntax features).
>
> I did have one question from it, which wasn't quite made clear in the
> interoperability section, or so it seems: how does the box `typed-context?`
> get into the modules that are not part of that language? Or more generally
> how would you solve this problem of needing to know which language of a
> module you are in without modifying the other languages? I was wondering if
> it was a hackaround or if there was a way to do generically in any language i
> might make.
>
> I grepped the source code and it looks like it's even exposed to the user in
> a function `syntax-local-typed-context?`, but i noticed that module never
> actually imports `typed-context?`.
>
> I suppose if it is a hack i could just reflect on the namespace to solve the
> problem, but i thought i would send a mail here to check.
>
> Thanks for the great work everyone!
>
> Nate
>
> --
> You received this message because you are subscribed to the Google Groups
> "Racket Developers" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to racket-dev+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/racket-dev/CAM-xLPpey6e2S_JsBi_ZA_0OAC%2Bh8NJDrVYRv63fWmYrWiig1A%40mail.gmail.com.
--
You received this message because you are subscribed to the Google Groups
"Racket Developers" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to racket-dev+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/racket-dev/CAK%3DHD%2BYrz9s4zWn3kPpRwX2B_mzZME4SYnmi2Qby6mWUZFAZ3g%40mail.gmail.com.
