As an update, I’ve made a bit more progress on this. I’ve implemented an 
impersonate-async-channel function, and I’ve actually included this in the 
exports from racket/contract. I also realized the blame information is correct, 
it works fine. Most of the other issues remain, as well as a few new questions:

There is no impersonate-evt function, so I’m not sure that my implementation 
will work. What should I do about this?
I’d assume this needs to be documented/tested as well. Where should those 
things be located?

> On Jan 14, 2015, at 23:44, Alexis King <> wrote:
> Currently, async channels do not have contracts to check their contents. This 
> is a problem for Typed Racket, and it prevents typed code from interacting 
> with code that produces async channels.
> I started looking into how to add contracts to the language, and it seems to 
> use the chaperones/impersonator system, as I suspected. However, async 
> channels obviously cannot be impersonated, so I needed to implement that as 
> well.
> I modified the async-channel struct to use generics to allow it to be 
> impersonated or chaperoned, which I have exposed by implementing 
> chaperone-async-channel. I then tried implementing async-channel/c. The 
> internals of the contract system are a little beyond me, but I got a working 
> solution by following the example of the box contracts.
> My work thus far can be found here: 
> <>
> First of all, is this a correct approach? Have I done anything wrong, or 
> should I have done anything differently? I didn’t find much documentation on 
> the internals of either of these systems, so I mostly went about things as I 
> found them.
> Second, obviously, not everything is implemented here. Among the additional 
> necessary changes are:
> I need to implement support for impersonators and impersonator contracts 
> (right now I’ve only bothered to do chaperones).
> I need to implement async-channel/c-first-order and async-channel/c-stronger. 
> I can probably figure out the latter, but I’m not even sure what the former 
> is supposed to do.
> I need to implement a wrap-async-channel/c macro for the export. I’m not sure 
> how this works, either. From looking at wrap-box/c, it seems to add some 
> syntax properties, but I’m not sure what they do or how they work.
> Somehow, the blame information has to be correct. Is that what the wrap 
> function does? Or do the async-channel functions need to be updated to assign 
> blame?
> I’d really like to get this working, and I think I’m close, but I’m a little 
> inexperienced. I’d appreciate any help, even if it’s just pointing me in the 
> right direction.
> Thanks!

  Racket Developers list:

Reply via email to