One reason you&#x27;re seeing slowness is that the compiler is undergoing an internal refactoring that will _completely change_ the way these kinds of features will be implemented. So they&#x27;re effectively on-hold-ish until after that&#x27;s done.<p>Also, this particular feature seems easy from a usage perspective, but the type theory behind it is actually pretty intense, and there&#x27;s multiple possible ways of doing it. So those need to be explored, discussed, and figured out.<p>This feature is one that&#x27;s of high importance, and is coming sooner rather than later.