Ask HN: Which technology are you learning or are you planning to learn?

I spent the last few months digging in a lot of different technologies during my spare time, just for curiosity, from Elixir to Kotlin, and abstractions, from Functional Reactive Programming to Event-driven Dataflow Programming also reading about the history behind them. After studying the latter, I actually decided to write a book about Reactive Programming in Swift, that is a work in progress, but that's another story.

I am a desperately curious developer and I was wondering which technology are you currently learning or are you planning to learn in the near future and why?