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. >>>>>>>> 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/D688771A-C477-40D8-B209-D9506362C5 >>>> CB%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/1AFE0571-C48C-4B22-B445-D96B283C68 >>>> 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 group, send email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/racket-dev/5915b006.5639620a.b51d4.83dcSMTPIN_ADDED_MISSING%40gmr-mx.google.com. >>> 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/CAL3TdOPTT8-8CuJt86VE-_z%3DnZ%2B-Hxf92HyNW%3DvUtiVy9-5yAg%40mail.gmail.com. >> 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/752ED434-8FB1-4F9A-89C2-153070098FF8%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/CAL3TdOOm1sH2GxLqn1ZtG49XUwSa_A2Pvo2Wp09Uzuw-zzL1zw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
