This means that trying to contract them will fail or that it will default
back to just protecting the underlying functions?

Jay

On Thu, May 11, 2017 at 11:16 AM Matthew Flatt <[email protected]> wrote:

> 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?
>
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-- 
-=[     Jay McCarthy               http://jeapostrophe.github.io    ]=-
-=[ Associate Professor        PLT @ CS @ UMass Lowell     ]=-
-=[ Moses 1:33: And worlds without number have I created; ]=-

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