Lisp Koans
Common Lisp Koans is a language learning exercise
...The feedback loop is intentionally tight: fail, reflect, fix, and rerun until the tests become a form of living documentation. Because koans are organized from fundamentals to metaprogramming, learners internalize not just syntax but also Lisp’s philosophy of code-as-data. The exercise format makes it ideal for workshops, katas, or leveling up engineers who have never touched a Lisp before. It’s minimal on infrastructure and maximal on discovery, encouraging use of a REPL and inspector while you solve each puzzle.