The Expression Problem provides a great test case for comparing Java, Scala, and Clojure. If you change an interface in Java, you have to update all implementations to reflect that change. See how traits are used to minimize these changes in Scala and how Clojure sidesteps a good portion of these issues (at the expense of run-time safety). Broaden your view of programming by seeing these three popular languages compared side-by-side against a long-standing problem (Further Details)