I was working on a clojure&#x2F;clojurescript app a while ago.  I was hoping to share code between the two.  This was pre-clj 1.7 with reader conditionals, so I did some manual footwork to try and resolve the small differences.  However the biggest issue I repeatedly ran into was libraries.  One of clj&#x27;s biggest strengths (and why it has an awesome library ecosystem) is that you can just nab a battle tested java lib and write a tiny clj wrapper around it.  Those libraries are, obviously, not going to run in js land.  As clj matures and we see more pure clj libraries the situation will hopefully improve, but I felt somewhat thwarted by my attempt.