Common Lisp Koans is a language learning exercise in the same vein as the ruby koans, python koans and others. It is a port of the prior koans with some modifications to highlight lisp-specific features. Structured as ordered groups of broken unit tests, the project guides the learner progressively through many Common Lisp language features.
I highly recommend these exercises!
The lisp koans project was an inflection point during my own journey to learn lisp; I leveled up by performing these exercises.
After completing these, I started writing my own lisp programs from scratch, to complete simple repetitive work.