Clojurescript node.js firmata message parser (incomplete)

message-parse.cljs

(defn parse-message
  "Parses incoming data and emits valid messages"
  []
  (let [data (js/Buffer 0)]
    (fn [emitter buffer]

      ;; Append new data to buffer
      (set! data (.concat js/Buffer [data buffer]))

      ;; Remove incomplete messages (ie. not control charactors)
      (while (> (.slice data 0 1) 127))
        (set! data (.slice data 1 (.length data)))

      (cond
       ;; analog/digital I/O message or set pin mode or protocol version
       (some #{byte} [0xE0 0x90 0xF4 0xF9])
       (if (>= (.length data) 3)
         (.emit emitter "data" (.slice data 1 3))
         (set! data (.slice 3 (.length data))))

       ;; report analog/digital pin
       (some #{byte} [0xC0 0xD0])
       (if (>= (.length data) 2)
         (.emit emitter "data" (.slice data 1 2))
         (set! data (.slice 2 (.length data))))

       ;; sysex start
       (= byte 0xF0)
       (if (= 0xF7 (.slice data (- 1 (.length data)) (.length data)))
         (.emit emitter "data" data)
         (set! data (js/Buffer 0)))

       ;; reset
       (= byte 0xFF)
       (do
         (.emit emitter "data" 0xFF)
         (set! data (.slice 2 (.data length))))))))