Taral wrote:
On 12/7/06, Chris Kuklewicz <haskell@list.mightyreason.com> wrote:
Small clarification: You don't need a safepoint in your code. But "unblock yield" is the right code for a safepoint; the "unblock (return ())" suggested by the published paper *does not work* in my small test, while "unblock yield" worked every time in a small test. Simon may updated the documentation eventually to reflect this.
I think people are misunderstanding the nature of a safepoint. The safepoint is a point at which you are prepared to have exceptions delivered. This does not mean that they *will* be delivered, just that they can. If you need to *wait* for an asynchronous exception, then you shouldn't be using them at all.
Right. If a thread mostly runs inside 'block' with the occasional safe point, then your exceptions are not really asynchronous, they're synchronous. In this case, I'd say a better solution is to have an explicit event queue, and instead of the safe point take an event from the queue. The action on receiving an event can be to raise an exception, if necessary. Cheers, Simon