> And I bet those green threads still need an IO type of some sort to encode anything non-pure, plus usually do-syntax.
There's no need for the do-syntax at all. The (IO a) is no different to other generic types that can be fmap-ed, pointfree-composed with other expressions, and joined/folded when required. The only difference is the fact that they represent actions that affect the real world, so that ordering of things suddenly becomes important.
Right, and there's also no need for await syntax at all, they can be then-ed, ContinueWith-ed or whatever the language calls them, but people keep bringing syntax into a semantics battle, so I had to mention it.
There's no need for the do-syntax at all. The (IO a) is no different to other generic types that can be fmap-ed, pointfree-composed with other expressions, and joined/folded when required. The only difference is the fact that they represent actions that affect the real world, so that ordering of things suddenly becomes important.