Clojurians Log v2

I usually use AOC to practice something new. I've used it to practice Haskell, Clojure, Rust, Vim, TDD. This year I don't have new things to practice. The only things that come to my mind is to try REPL driven development instead of TDD, maybe macros, transducers, ClojureScript, core.async.

Do you have a personal challenge this year?

For me it's Clojure in general + REPL driven development

Who all is playing this year?