Well, we are fortunate that the author covered four languages. That said, seeing the same in Julia and also Common Lisp would be great. I am coming up on my 36 year anniversary for using Common Lisp, so even though I really love Haskell and Racket, and I am enjoying learning Julia, I would vote for adding CL.

This might be a good community project - the article on github and allow people to do pull requests adding their favorite language.