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.
