Yes, that's control flow magic. It was prototyped with a macro, but failure handling comes up all the time in practical programming, and it's important to make it as ergonomic as possible.
I see. I think reading your initial comment I took issue with the hyperbole "crazy control-flow (monadic) magic is happening here".
But yes it is a hidden control flow, and taking in account hidden control flows is inherently more complicated (or at least has a steeper learning curve).
But yes it is a hidden control flow, and taking in account hidden control flows is inherently more complicated (or at least has a steeper learning curve).