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 <lexi.lam...@gmail.com> 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: > https://github.com/lexi-lambda/racket/commit/84b9f3604891f3f2061fb28ed4800af8afa4751b > > <https://github.com/lexi-lambda/racket/commit/84b9f3604891f3f2061fb28ed4800af8afa4751b> > > 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!
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