What I was trying to say is that in the olden days of say the 80s, Mac OS used cooperative threads and you just wrote a main loop that was completely self-contained. We made OS calls from there, the OS didn't call us with events like it does today (at least most of the time). So programs were much simpler to debug because we didn't have callback or goto hell.
The tradeoff was that it took pages of boilerplate to make even the simplest app, and Apple got made fun of incessantly for it. So they largely fixed that with OS X's message passing metaphors, but unfortunately due to bloat and a lot of other reasons, the boilerplate issue came back, and now we're also stuck with untraceable program flow.
To answer the original question - I have worked on both blocking and nonblocking code, and unfortunately nonblocking code doesn't scale. It eventually becomes too complex to follow the flow. It's like comparing a coroutine to a state machine. My personal feeling is that we're in a kind of nonblocking bubble right now and that the callback style that pretty much all frameworks use today is not going to be the way it's done in the future. I don't know what will replace it, but it will likely be something more like Redux/Elm/Clojure and declarative GUI syntax like how the web used to work.
The tradeoff was that it took pages of boilerplate to make even the simplest app, and Apple got made fun of incessantly for it. So they largely fixed that with OS X's message passing metaphors, but unfortunately due to bloat and a lot of other reasons, the boilerplate issue came back, and now we're also stuck with untraceable program flow.
To answer the original question - I have worked on both blocking and nonblocking code, and unfortunately nonblocking code doesn't scale. It eventually becomes too complex to follow the flow. It's like comparing a coroutine to a state machine. My personal feeling is that we're in a kind of nonblocking bubble right now and that the callback style that pretty much all frameworks use today is not going to be the way it's done in the future. I don't know what will replace it, but it will likely be something more like Redux/Elm/Clojure and declarative GUI syntax like how the web used to work.