Off-topic, but the idea of "colored functions" from the "What Color is Your Function" article doesn't apply to Rust's async/await. That article is about JavaScript before it had async/await, when it used callbacks.

In Rust, you can call async functions from normal ones by spawning them on the executor. The .await syntax isn't as painful as dealing with callbacks and closures in JavaScript. Plus, if you call an async function incorrectly, Rust's compiler will catch it and give you a clear error message, unlike JavaScript, where bad function calls could lead to unpredictable behavior. The premises of the article don't apply, so Rust's async/await doesn't introduce the same "colored function" issues.

(See also https://without.boats/blog/let-futures-be-futures/ )