On 2012-08-30 06:53:58 -0600, Matthew Flatt wrote: > I think this combination of replacing both `call/cc' and `dynamic-wind' > would be equivalent to a smaller change to the semantics of `call/cc', > which is that it behaves as it does now if there's a shared > `dynamic-wind' between the source and target continuations, but it > behaves like your replacement `call/cc' if there's no intervening > prompt (which addresses the reasoning problem). Also, implementing the > change directly in the existing `call/cc' implementation sounds fairly > easy to me.
Sam and I discussed this some more, and we think it sounds workable and will go and try to add it to the Redex model and see what tests fail. We were concerned about one thing though: it sounds like this would modify the behavior of `call/cc` depending on whether or not you put a `dynamic-wind` in your continuation. That also means that a programmer who installs a `dynamic-wind` might get fewer abort handlers run than expected, or perhaps gets *more* run than expected since they either didn't install the `dynamic-wind` or they passed the continuation out of the `dynamic-wind` to a different context and invoked it there. Is that a fair point or are we misunderstanding your proposed semantics? Cheers, Asumu _________________________ Racket Developers list: http://lists.racket-lang.org/dev
