So basically UI programmers are used to callbacks, others not that much, and now that event-loop servers are becoming popular, we see confusion from people not familiar with events.
I don't think that's right. There is a huge difference. UI callbacks ("onClick" and the like) execute synchronously. But the callbacks in event servers execute at completely different times. Indeed, they're typically nested inside code that has long since terminated. This is what causes the learning curve, not grokking events or functions-as-values, which any half-decent programmer can easily do in the unlikely event that they didn't a long time ago. Indeed, the way we write asynchronous callbacks is cognitively dissonant with everything we've been trained to understand about scoping. The idea of a nested scope that doesn't mean "contained within" or "covered by", but rather "at some unknown time later", is inconsistent enough with how programming languages normally work that it can easily trip you up even after you get good at it.
Asynchronous programming is a very different thing than e.g. browser UIs in Javascript. I've programmed those for years. It still took me a long time to get my head around async servers.
I don't think that's right. There is a huge difference. UI callbacks ("onClick" and the like) execute synchronously. But the callbacks in event servers execute at completely different times. Indeed, they're typically nested inside code that has long since terminated. This is what causes the learning curve, not grokking events or functions-as-values, which any half-decent programmer can easily do in the unlikely event that they didn't a long time ago. Indeed, the way we write asynchronous callbacks is cognitively dissonant with everything we've been trained to understand about scoping. The idea of a nested scope that doesn't mean "contained within" or "covered by", but rather "at some unknown time later", is inconsistent enough with how programming languages normally work that it can easily trip you up even after you get good at it.
Asynchronous programming is a very different thing than e.g. browser UIs in Javascript. I've programmed those for years. It still took me a long time to get my head around async servers.