[dwattttt]

Yes, it's quite curious. Having used both block_on and spawn_blocking, and not being worried about what "colour" my function is, I am also quite confused about the fuss.

On a practical note, since Rust doesn't standardise on an async runtime, it would be more accurate to say tokio solved the coloured function problem, for whatever that means. Or any and everyone else that made it easy to call one coloured function from another.