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-4900-8215-198f77d9b991%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-D9506362C5CB%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-D96B283C6885%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-B65BCF8BE695%40ccs.neu.edu. For more options, visit https://groups.google.com/d/optout.
