Some interesting things happening in the structured concurrency / "Direct style" space. It looks like it could become a powerful and readable way to compose (asyncy type) things. Simpler code, usable stack traces, better traceability, less function colouring concerns.

It's early days in that regard, with some folks doing some really interesting things: Odersky himself / the Ox project.

With OCaml 5 and effects it might be possible to use direct style, and rely on effect handlers to schedule IO. Here is an example of how structured concurrency in OCaml could look like https://ocaml.org/p/picos_std/latest/doc/Picos_std_structure...