It would also be great to see example code for that - it's the most significant part where I was looking for more information but couldn't find it.
Edit: A bit unrelated, but the tokio vs async-std split continues!
Edit 2: How does error handling work? Is check_login a component or regular request?
Async UI as a whole is inspired by the simple fact that UI is an effect system[1], and async is also an effect system.
[1]: https://en.wikipedia.org/wiki/Effect_system
Re async split: Diversity promotes innovation :)
Re error handling: There's no real support yet. For now when I hit an error I just render nothing. I might add support for components returning Result<_, _> in the future.
(except for that invalid_login_popup is not a real popup because I haven't implemented popups yet)
I'll add a link to it in the blog post.
Concretely the login_form function works by racing a render (a true, never-completing component) with a "listener" future that completes when the user submits their login. Once the listener completes, the race is over and the render future gets dropped. We can then return from login_form.