Cool stuff! I work with @jpolitz and @enum on the Stopify project as well. Early on we also implemented a similar generator approach to what you described (as

Cool stuff! I work with @jpolitz and @enum on the Stopify project as well. Early on we also implemented a similar generator approach to what you described (as well as CPS). We found that it mostly worked, but had a few drawbacks. Specifically, generators change the type of instrumented functions, which makes it difficult to implement constructors and prototype inheritance, and they also break tail calls in environments that support them. More importantly for practical concerns, we found it to be much slower (at least 2x-3x) than the solution we came up with. Again, happy to share more information with you!