### `typealias` in entry point struct The idea here would be to have the `@main` `struct` declare the executor type that it wants. This is straightforward for users, _but_ doesn't work for top-level code, and also doesn't allow the user to change executor based on configuration (e.g. "use the `epoll()` based executor, not the `io_uring` based executor"), as it's fixed at compile time.