When I wrote that I didn’t really understand the difference in terminology between “effects”/“effect types” (e.g. keyword-based modifiers on functions and types) and “effect handlers” (e.g. typed co-routines).

Many effectful languages have both, so teasing them apart can be confusing. I think I can now more comfortably say that what we’re working on is an extension to Rust’s effect system. This has nothing to do with effect handlers.