I'm not sure what you mean by continuation-based. The Arc server can use closures to store state, but it doesn't use continuations.
Using closures to store state is like using lists as data structures: it's a rapid prototyping technique. You're in no way painting yourself into a corner, and the current news software is proof of that. You have a very old version of it. In the years since we released the version you have, we've gradually squeezed most of the closures out of the more common things, and we do have a proxy in front of the Arc server. That's how we manage to serve 1.7 million pages a day off one core.
Using closures to store state is like using lists as data structures: it's a rapid prototyping technique. You're in no way painting yourself into a corner, and the current news software is proof of that. You have a very old version of it. In the years since we released the version you have, we've gradually squeezed most of the closures out of the more common things, and we do have a proxy in front of the Arc server. That's how we manage to serve 1.7 million pages a day off one core.