> 1. Many languages don't support this (including Go and Lua, AFAIK). I don't think this is necessarily a property of the primitives. greenlet doesn't support

> 1. Many languages don't support this (including Go and Lua, AFAIK). I don't think this is necessarily a property of the primitives. greenlet doesn't support anything like gevent.joinall(gevent.spawn(foo()), gevent.spawn(bar()), but gevent does by adding python code to greenlet. So I'm sure that in the same manner one could do it in Lua using Lua's coroutines. (There might be some concern that we have the wrong primitive: greenlet provides symmetric coroutines and Lua provides asymmetric coroutines. I don't think it matters for this which one we use, but if it does it is simple to implement either in terms of the other.) That's not to say that the situation is ideal! To a great extent it's good if a language comes with a standard way to do this stuff! But it would be silly to say something like "Lua doesn't have inheritance" because it has a DIY inheritance construction kit instead of an "extends" keyword.