While I agree with his points in principle, Rust isn't actually a great example to use. Rust allows to simply spawn threads, right? So a function not being mar

While I agree with his points in principle, Rust isn't actually a great example to use. Rust allows to simply spawn threads, right? So a function not being marked 'async' doesn't necessarily give any guarantees about potential side effects. Spending most of my time writing Elm, having side-effects present in the type system is great. But colored functions in Rust (as well as most other async/await langs) only creates a devide between functions that provide a specific kind of asynchrony, and those which do not. So async/await improves the syntax of writing a specific kind of async code, at the cost of composability (the red/blue divide). It does not, however, make any guarantees about the asynchronous nature of your code.