Only because you asked, this has been my pet project :)
Using Artificial Intelligence to Write Self-Modifying/Improving Programs
Using Artificial Intelligence to Write Self-Modifying/Improving Programs
Have you seen Clojush? It's "the Push programming language and the PushGP genetic programming system implemented in Clojure." I haven't had a chance to play with it yet, but it seems to be in active development. https://github.com/lspector/Clojush