I think the point is that this is intentional. I love super high-level languages, but they're experimental for a reason -- things haven't 'settled down yet' and

I think the point is that this is intentional. I love super high-level languages, but they're experimental for a reason -- things haven't 'settled down yet' and until they do, it will be difficult for the average person to reason about what is going on. No, sorry, I should have been even more explicit: it looks like the designers were not even aware of new advances in PLT. As far as I can see, defer/panic/recover is objectively worse than an exception system for all of the goals which they lay out in their paper. You like return values--ok, I can see that. I prefer that the type checker actually enforce error checking when using error return values, but fine. Adding defer/panic/recover is an attempt to add a simpler and more constrained exception-like system to the language, but I think it is objectively (both from a PLT perspective and compiler-design perspective) worse than a more traditional exception system. Breaking beta-reduction is very unfortunate and I can't see a good reason to do it in this case.