Cond looks a lot like the Clojure error-kit library:

    (deferror divide-by-zero
      {:msg "Division by zero})

    (defn divide [x y]
      (if (zero? y)
        (raise divide-by-zero)
        (/ x y)))

    (with-handler
      (divide 10 2)
      (divide 18 3)
      (divide 4 0)
      (divide 7 0)
      (handle divide-by-zero
        (continue-with 42)))

Admittedly this doesn't violate your general point; there are things like continuations that are hard to do with Clojure due to limitations the JVM. However, I tend to find there aren't many things Clojure can't do, and in general it seems more flexible and better designed than Ruby.