- Spanish (I'm halfway decent but still struggle especially with production and spoken comprehension)

- Japanese (I'm still rather bad, although I know a fair bit of Kanji, vocab and grammar by now)

- Mathematical Logic (very vast topic)

- Programming Language theory, Type theory, better understanding of functional programming language concepts, etc. I'd like, for example, to be able to be productive in Haskell.

- Distributed systems. I'm really bad at thinking about distributed computing (although I suspect that even most people who work on distributed systems are), so I'd like to improve. I'm currently reading "The Art of Immutable Architecture" which, maybe unexpectedly, is mostly about how immutability helps with distributed computing. It's definitely idiosyncratic though, so I'll also need to read some other stuff. I've had my eyes on "designing data-intensive applications" for a while now. I'd also like to learn some Erlang/Elixir at some point.

- History. I'm really interested in history and enjoy good podcasts, audiobooks etc. about it. Currently on the Russian Revolution and also listening to a lecture series on the middle ages.