Can confirm. ;) On May 12, 2017, 1:13 PM -0400, Sam Tobin-Hochstadt <[email protected]>, wrote: > The problem with Typed Racket would come from sending a higher order value to > an untyped thread. I'm pretty sure you could get unsoundness there. > > > On Fri, May 12, 2017, 12:00 PM Matthias Felleisen <[email protected]> > > wrote: > > > > > > I cannot turn this one into a problem with Typed Racket though. th must > > > have type Thread and the -> Any of thread-receive requires a cast > > > already, which covers our ‘soundness’ behind. > > > > > > > > > > > > > > > > On May 12, 2017, at 11:38 AM, Robby Findler > > > > <[email protected]> wrote: > > > > > > > > Yeah, that's a real one. :) > > > > > > > > Robby > > > > > > > > On Fri, May 12, 2017 at 10:30 AM, Scott Moore <[email protected]> > > > > wrote: > > > >> Reading a bit further in the docs, there is a bigger hole: > > > >> > > > >> (define (component-1 value channel) > > > >> (thread-send channel value)) > > > >> > > > >> (define-values (component-2 channel) > > > >> (let () > > > >> (define main (current-thread)) > > > >> (define th > > > >> (thread (lambda () (thread-send main (thread-receive))))) > > > >> (values (lambda () (thread-receive)) th))) > > > >> > > > >>> (component-1 (lambda () "hello world") channel) > > > >>> ((component-2)) > > > >> "hello world" > > > >> > > > >> On May 12, 2017, 11:05 AM -0400, Matthias Felleisen > > > >> <[email protected]>, > > > >> wrote: > > > >> > > > >> > > > >> What your (cool little) program demonstrates is that *information* can > > > >> flow > > > >> from one thread to another, not *data*. You need to convince me that > > > >> data > > > >> flows and then we need to figure out how to protect/monitor this data. > > > >> And > > > >> at that point, you can possibly see lambdas flow too. > > > >> > > > >> > > > >> > > > >> On May 12, 2017, at 11:02 AM, Scott Moore <[email protected]> wrote: > > > >> > > > >> I think the interesting distinction is that threads, regexps, ports, > > > >> etc, > > > >> are communication channels, but not for higher-order values. > > > >> > > > >> On May 12, 2017, 10:58 AM -0400, Scott Moore <[email protected]>, > > > >> wrote: > > > >> > > > >> (define (component-1 value) > > > >> (define t > > > >> (thread (lambda () > > > >> (thread-suspend t) > > > >> (for ([i (in-range value)]) > > > >> (thread-suspend t))))) > > > >> t) > > > >> > > > >> (define (component-2 thread) > > > >> (thread-resume thread) > > > >> (let* ([suspend-evt (thread-suspend-evt thread)] > > > >> [dead-evt (thread-dead-evt thread)] > > > >> [result (sync suspend-evt dead-evt)]) > > > >> (if (eq? result dead-evt) > > > >> 0 > > > >> (add1 (component-2 thread))))) > > > >> > > > >> (define t (component-1 2)) > > > >> (component-2 t) > > > >> > > > >> 2 > > > >> > > > >> (define t (component-1 5)) > > > >> (component-2 t) > > > >> > > > >> 5 > > > >> > > > >> On May 12, 2017, 10:46 AM -0400, Robby Findler > > > >> <[email protected]>, wrote: > > > >> > > > >> I would say that the event value is the channel of communication. But, > > > >> if this expression: > > > >> > > > >> (sync (thread (lambda () 3))) > > > >> > > > >> returned 3, then I'd say that thread itself is a channel of > > > >> communication. But threads give themselves back to sync, not the > > > >> values that their thunks return. > > > >> > > > >> Robby > > > >> > > > >> On Fri, May 12, 2017 at 9:41 AM, Matthias Felleisen > > > >> <[email protected]> wrote: > > > >> > > > >> > > > >> I tend to agree though there is some information flowing from a thread > > > >> to > > > >> its context (thread CML events). I have to think whether this is a > > > >> channel > > > >> of communication. > > > >> > > > >> > > > >> > > > >> > > > >> On May 12, 2017, at 8:57 AM, Robby Findler > > > >> <[email protected]> > > > >> wrote: > > > >> > > > >> This perspective suggests a gap in the design in some sense, I would > > > >> say. The PL construct cannot, on its own, guarantee that the values > > > >> from #:authentic structs end up behaving like those kinds of values. > > > >> > > > >> (also: threads and regexps don't seem problematic from the contract > > > >> perspective, but ports do, since they are a communication channel and > > > >> the others aren't.) > > > >> > > > >> Robby > > > >> > > > >> > > > >> On Fri, May 12, 2017 at 7:52 AM, Matthew Flatt <[email protected]> > > > >> wrote: > > > >> > > > >> I think a better analogy is to values like #<thread>, #<input-port>, or > > > >> #<regexp>. Although those kinds of values are implemented with structs, > > > >> the accessor and mutator functions are not exported (and, as Scott > > > >> says, there's no way to get the accessors and mutations by reflection), > > > >> so there's no way to impersonate the values. In general, it's up to the > > > >> implementation of a new kind of value to supply impersonator/chaperone > > > >> support for those values, and implementations usually don't. > > > >> > > > >> At Thu, 11 May 2017 19:00:43 -0400, Matthias Felleisen wrote: > > > >> > > > >> > > > >> Oh right. > > > >> > > > >> > > > >> On May 11, 2017, at 6:54 PM, Robby Findler <[email protected] > > > >> > > > >> wrote: > > > >> > > > >> > > > >> They would be the same. We currently cannot chaperone or impersonate > > > >> cons > > > >> > > > >> cells. We copy them. > > > >> > > > >> > > > >> Robby > > > >> > > > >> On Thu, May 11, 2017 at 5:51 PM Matthias Felleisen > > > >> <[email protected] > > > >> > > > >> wrote: > > > >> > > > >> > > > >> Yes except that you can contract cons cells. So why couldn’t you > > > >> contract > > > >> > > > >> authentic structs then? > > > >> > > > >> > > > >> > > > >> > > > >> On May 11, 2017, at 6:41 PM, Robby Findler <[email protected] > > > >> > > > >> wrote: > > > >> > > > >> > > > >> Indeed: if we did that, then these structs would be much like cons > > > >> cells currently are. > > > >> > > > >> Robby > > > >> > > > >> > > > >> On Thu, May 11, 2017 at 5:39 PM, Robby Findler > > > >> <[email protected]> wrote: > > > >> > > > >> What if #:authentic (or whatever) were only allowed on immutable > > > >> objects and we allowed them to be copied? Then contracts could protect > > > >> them. > > > >> > > > >> Robby > > > >> > > > >> > > > >> On Thu, May 11, 2017 at 5:38 PM, Matthias Felleisen > > > >> <[email protected]> wrote: > > > >> > > > >> > > > >> @ Christos > > > >> > > > >> #:authentic explicitly introduces a channel of communication that it is > > > >> > > > >> not protectable by contracts. This makes Racket’s contract system > > > >> explicitly > > > >> incomplete. It might have been incomplete in the past for other > > > >> reasons. > > > >> > > > >> > > > >> If the name isn’t fixed, #:no-proxy-allowed would be my preference. > > > >> > > > >> — Matthias > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> On May 11, 2017, at 12:48 PM, Scott Moore <[email protected] > > > >> > > > >> wrote: > > > >> > > > >> > > > >> I agree that generally don't want performance declarations that > > > >> interfere with reasonable interposition. The good uses of `#:authentic` > > > >> would be in places where the struct representation of a value is not > > > >> exposed or where the values themselves are not exposed (so any > > > >> interposition means being on the "inside" where you can change the > > > >> code, anyway). > > > >> > > > >> > > > >> Yes, I agree with this. I think as far as how this changes Racket’s > > > >> > > > >> data abstraction model, the key is “where the values themselves are not > > > >> exposed.” > > > >> > > > >> #:authentic only has an interesting effect in the other case, where > > > >> > > > >> “outside” code gets its hands on a value of the struct type. > > > >> Previously, I > > > >> could write a program that used inspectors to impersonate this value > > > >> regardless of the “inside” code’s intent. Now that would no longer be > > > >> possible. > > > >> > > > >> > > > >> I doubt there is much code that currently relies on being able to do > > > >> > > > >> this and so I would say go ahead. (Perhaps DrRacket or other debugging > > > >> tools?) > > > >> > > > >> > > > >> On the other hand, Spencer already asked if this would be something the > > > >> > > > >> optimization coach would recommend. I think it would be important for > > > >> the > > > >> documentation of #:authentic or the implementation of such a coach to > > > >> stress > > > >> the importance of the rules of thumb you just laid out. > > > >> > > > >> > > > >> -- > > > >> 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 [email protected]. > > > >> > > > >> To post to this group, send email to [email protected]. > > > >> To view this discussion on the web visit > > > >> > > > >> https://groups.google.com/d/msgid/racket-dev/3c430798-e93a-4900-8215-198f77d9b9 > > > >> 91%40Spark. > > > >> > > > >> For more options, visit https://groups.google.com/d/optout. > > > >> > > > >> > > > >> -- > > > >> You received this message because you are subscribed to the Google > > > >> > > > >> Groups "Racket Developers" group. > > > >> > > > >> 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85%40ccs.neu.edu. > > > >> > > > >> For more options, visit https://groups.google.com/d/optout. > > > >> > > > >> > > > >> -- > > > >> 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 [email protected]. > > > >> To post to this group, send email to [email protected]. > > > >> To view this discussion on the web visit > > > >> https://groups.google.com/d/msgid/racket-dev/77B4F4BC-74B9-4838-AFC1-B65BCF8BE6 > > > >> 95%40ccs.neu.edu. > > > >> For more options, visit https://groups.google.com/d/optout. > > > >> > > > >> > > > >> -- > > > >> 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 [email protected]. > > > >> To post to this 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