Well, better late than never. Stuff like sets or a typed heap is long overdue. Maybe they'll even add iterator API for database/sql results this decade too (something like my pull request for sqlx https://github.com/jmoiron/sqlx/pull/990 but maybe more polished)
Also having stuff like a concurrency limiter (instead of doing weird var limiter chan struct{} and using it as `limiter <- struct{}{}` and `defer <-limiter`) as a library function in `sync` package would be great too.
there's https://pkg.go.dev/golang.org/x/time/rate ...
But I guess the issue is that oftentimes, it is more of a distributed system coordination issue?
What use case do you have in mind?