Converting a byte array to a UUID

bytes->uuid.clj

(defn byte->long [b] (if (neg? b) (+ 256 b) b))

(defn bytes->long
  [bytes]
  {:pre [(= 8 (count bytes))]}
  (apply + (map bit-shift-left (reverse (map byte->long bytes)) (range 0 64 8))))

(defn bytes->uuid
  [bytes]
  (java.util.UUID. (bytes->long (take 8 bytes))
                   (bytes->long (drop 8 bytes))))

;; usage

(def bytes (into-array Byte/TYPE [48 3 94 -5 34 -109 68 95 -97 -91 -110 42 43 52 119 -117]))

(bytes->uuid bytes)

;; => #uuid "30035efb-2293-445f-9fa5-922a2b34778b"