Clojure code to convert a byte array to an integer

bytes_to_int.clj

(defn bytes-to-int
  ([bytes]
     (bytes-to-int bytes 0))
  ([bytes offset]
     (reduce + 0
             (map (fn [i]
                    (let [shift (* (- 4 1 i)
                                   8)]
                      (bit-shift-left (bit-and (nth bytes (+ i offset))
                                               0x000000FF)
                                      shift)))
                  (range 0 4)))))