> 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 al

> 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.