gistfile1.clj

(defn separate-2 [f coll]
  (loop [coll coll
         in nil
         out nil]
    (if (empty? coll)
        [(reverse in) (reverse out)]
        (let [cur (first coll)]
          (if (f cur)
              (recur (rest coll) (cons cur in) out)
              (recur (rest coll) in (cons cur out)))))))