example.clj

(defsynth foo [freq 200 dur 1]
  "
  defines the foo synth. Taken from the Overtone example
  https://github.com/overtone/overtone/blob/master/src/overtone/examples/getting_started/basic.clj
  "
  (let [src (saw [freq (* freq 1.01) (* 0.99 freq)])
        low (sin-osc (/ freq 2.1))
        filt (lpf src (line:kr (* 10 freq) freq 10))
        env (env-gen (perc 0.1 dur) :action FREE)]
    (out 0 (pan2 (* 0.8 low env filt)))))


(defn fun
  "
   A helper function that accepts 2 arguments `time` and `freq`;
   it plays `freq` at `time`. `time` is a Unix timestamp. ie 1393403168019
   http://en.wikipedia.org/wiki/Unix_time
  "
  [time freq]
  (at time
      (foo freq 1))
  )


(defn cycle-plus
  "returns a lazy sequence of `start` added to each consecutive
  item in `args`, which is a collection or a lazy sequence."
  [start args]
  (lazy-seq
   (cons start (cycle-plus (+ start (first args)) (drop 1 args)))
   )
  )


;; Below we call the function that accepts a time and a frequency 1000 times with consecutive items from
;; 2 lazy sequences. The first repeatedly adds 100 and 333 milliseconds to the current time. The second
;; alternates the frequency, in Hertz, in the vector given.
;; 
;;    call function     1000 times             repeat every ms       repeat frequencies
(map #(fun %1 %2) (take 1000 (cycle-plus (now) (cycle [100 333]) )) (cycle [200 220 300 270 280 600 220 430 800 500 333]))