I recommend checking out uiua.org for fun. The docs are well written and the concepts, while foreign to most, are ultimately accessible and interesting.
k and uiua are in different branches of the APL family.
I recommend checking BQN at https://mlochbaum.github.io/BQN/ and the YouTube channel code_report by Conor Hoekstra (and also "Composition Intuition by Conor Hoekstra | Lambda Days 2023"). It is well documented.
k and uiua are in different branches of the APL family.