Higher-kinded types themselves, not necessarily, but the abstractions they afford are, once you've gotten used to them, a huge time saver. I've gotten used to

Higher-kinded types themselves, not necessarily, but the abstractions they afford are, once you've gotten used to them, a huge time saver. I've gotten used to handling concurrency as a monad, for example, and honestly dread the time when I have to manually deal with manual synchronisation again.