There are many structure types that are private to some library (such as the expander) and will never have impersonators. The compiler can't know that, though, and the possibility of an impersonator means that the structure type's predicate has to be twice as expensive. Field selection is also more expensive in certain cases. I'm not sure about the current Racket VM, but the cost is measurable when running the Racket expander on Chez Scheme.
So, I'm thinking of adding a `prop:authentic` structure type property --- with an `#:authentic` shorthand for `struct` --- that prevents instances of a structure type from being impersonated or chaperoned. Naturally, an authentic structure type's supertype and subtypes must also be authentic. Any opinions? -- 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 racket-dev+unsubscr...@googlegroups.com. To post to this group, send email to racket-dev@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-dev/59148060.14da620a.a334b.158bSMTPIN_ADDED_MISSING%40gmr-mx.google.com. For more options, visit https://groups.google.com/d/optout.
