Not a Javascript library. The post advocates generators for Javascript programmers. For core.async to tell us the efficiency of JS code of this style, it'd need to expose a generator-based interface and compile to generator-based code like a human writes. If I understand right, it doesn't, and the JS libraries that do work this way are much less efficient when full stack traces are turned on. (If there are others, I hope someone will chime in.)

If you think those two libraries are just bad, I'll update somewhat in that direction.