Is it just me or do the first few examples seem worse than doing the same things without effects?

I can have a function fail by having it invoke an “exception” effect that doesn’t continue it. Or I can return a result and have that result contain the failure. If I use effects, I need to thread the effect through the call tree. (The effect has one nice property that a stack trace may be available, but this has runtime cost.)

If I’m writing a generator, then I can express it with effects, but it’s not immediately obvious to me that the resulting in-progress generation can be captured as a first-class value, whereas a conventional Iterable can, even in languages like Rust without a heavy runtime. (Maybe it’s in the article.)

And effects that continue twice are gross. Okay, there are cases where a continuation wants to be continued more than once and that a full-powered continuation should be used instead of a some more restrictive at-most-once or exactly-once scheme, but the function being continued really needs to be prepared for it, and the compiler cannot generate decent code without knowing how many times something can return. And I don’t see anything in the declaration of effects that gives any bounds on number of times that something can be continued.