I'm mildly comfortable with clojure, but haven't used it in a number of years. The code linked here looked pretty typical to me; could you possibly elaborate on

I'm mildly comfortable with clojure, but haven't used it in a number of years. The code linked here looked pretty typical to me; could you possibly elaborate on the differences between this and some more modern clojure, or maybe a reputable link to a blog post outlining the ways the language has changed?