This Code Kata is Roy Osherove's String Calculator. See http://osherove.com/tdd-kata-1
At my previous employer, in 2014-2016, we used to practice Code Katas with a twist:
Live coding in front of an audience of colleagues!
Sessions were fun (the Thursdays during the Brown Bag time-slot), and it was a good way to discover new languages and paradigms. We coded the String Calculator with at least 20 different languages, from x86 Assembly (yes) to Monadic Parsers in Haskell via RPG (Arhh!), Rust, Elixir and many more (including the more common languages obviously).
Even if we would have practised the Kata on our own before, to be in the hot seat was always pushing people out of their comfort zone.
This repo includes different versions: Non Monadic, and Monadic ones, including 2 written during live coding sessions.
In a previous session, I wrote the Kata in Ruby, including a one liner: