cond.clj

Which do you like better? Will the second have issues if the user has an unusual ns declaration, in which clojure.core/cond is not mapped?

(defmacro cond [& clauses]
  (if-not (even? (count clauses))
    (throw (IllegalArgumentException. "cond requires an even number of forms"))
    (reduce (fn [else [test then]]
              `(if ~test ~then ~else))
            nil
            (reverse (partition 2 clauses)))))

(defmacro cond [& clauses]
  (when clauses
    (list 'if (first clauses)
          (if (next clauses)
            (second clauses)
            (throw (IllegalArgumentException.
                    "cond requires an even number of forms")))
          (cons 'clojure.core/cond (next (next clauses))))))