[racket-dev] [racket] Implementing contracts for async channels

I already used blame-add-context, but the message I used wasn’t very good, so I’ve improved it. If everything else looks good, feel free to merge this whenever you get the chance!

> On Jan 19, 2015, at 15:52, Robby Findler <robby at eecs.northwestern.edu> wrote:
> 
> Ah: one other note. When you do something like this:
> 
> ((contract (-> (list/c (box/c integer?)) any)
>           (λ (x) (unbox (car x)))
>           'pos 'neg)
> (list (box "not an integer")))
> 
> you get an error message that has this text in the middle:
> 
>  in: the content of
>      the 1st element of
>      the 1st argument of
>      (-> (list/c (box/c integer?)) any)
> 
> This path information is collected in the blame records.
> 
> So, instead of passing along just the blame record you got, call
> "blame-add-context" so you get some stuff in that portion of the error
> message.
> 
> Maybe "a value passed on" or something like that would be a good
> phrase? I usually look at a few examples to pick something.
> 
> Otherwise, this looks good to merge to me (but I don't use the
> generics as much as I should so if you wanted to you could try asking
> for someone specifically knowledgeable to look there).
> 
> If you don't, I can push the commit to the appropriate repo. Let me know.
> 
> Robby
> 
> 
> 
> On Mon, Jan 19, 2015 at 5:44 PM, Alexis King <lexi.lambda at gmail.com> wrote:
>> Yes, there are tests, and you can see them here.
>> 
>> On Jan 19, 2015, at 13:29, Robby Findler <robby at eecs.northwestern.edu>
>> wrote:
>> 
>> This seemed okay, but just a quick read of the code. But did I miss
>> the test cases? (I just followed the link upthread -- sorry if I need
>> to look somewhere else too.)
>> 
>> Robby
>> 
>> 
>> On Mon, Jan 19, 2015 at 3:15 PM, Alexis King <lexi.lambda at gmail.com> wrote:
>> 
>> Any update on this? If there’s anything that still needs to be changed, let
>> me know—otherwise, I’ll patiently wait for the process to run its course.
>> Just checking in.
>> 
>> On Jan 16, 2015, at 10:15, Alexis King <lexi.lambda at gmail.com> wrote:
>> 
>> Ah, that makes sense, fixed.
>> 
>> On Jan 16, 2015, at 05:37, Robby Findler <robby at eecs.northwestern.edu>
>> wrote:
>> 
>> One comment. The contract combinators are curried so that you can do
>> work on the partial applications. So don't write this:
>> 
>> (define ((((ho-val-first-projection
>> impersonate/chaperone-async-channel) ctc) blame) val)
>> 
>> instead try to do some work earlier, when you first can. (The most
>> important thing is to minimize the work done after you get the 'val'
>> argument.)
>> 
>> Robby
>> 
>> 
>> 
>> 
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