People should try Janet (the programming language). Its fiber abstraction got everything right IMO.

Functions in Janet don't have "colors", since fiber scheduling is built-in to the runtime in a lower level. You can call "async" functions from anywhere, and Janet's event loop would handle it for you. It's so ergonomic that it almost feels like Erlang.

Janet has something akin to Erlang's supervisor pattern too, which, IMO, is a decent implementation of "structured concurrency" mentioned in the article.