Mary had a little lamb in overtone

mary.clj

(ns overtone-tutorial.mary)

(use 'overtone.core)
(boot-external-server)


(definst saw-wave [freq 440 attack 0.01 sustain 0.4 release 0.1 vol 0.4]
  (* (env-gen (lin-env attack sustain release) 1 1 0 1 FREE)
     (saw freq)
     vol))

;; Define a function for convenience
(defn note->hz [music-note]
  (midi->hz (note music-note)))

;; Let's make it even easier
(defn saw2 [music-note]
	(saw-wave (midi->hz (note music-note))))

(defonce metro (metronome 120))
(metro)


(def mary-notes [:E3 :D3 :C3 :D3 :E3 :E3 :E3 nil :D3 :D3 :D3
                 nil :E3 :G3 :G3 nil :E3 :D3 :C3 :D3 :E3 :E3
                 :E3 :E3 :D3 :D3 :E3 :D3 :C3])

(defn song-player [m beat-num notes]
  (map-indexed (fn [idx note]
                  (when note
                    (at (m (+ idx beat-num)) (saw2 note))))
               notes))

(song-player metro (metro) mary-notes)

Cool!

Is there any reason you used an external server rather than the internal one?

Also, your song-player relies on the REPL forcing the evaluation of the lazy sequence returned by map-indexed and uses the metro as a glorified lookup table - scheduling all events to happen ahead of time. This is a similar approach to that used by Chris Ford in his compositions. An alternative is to use what's known as temporal recursion which involves schedule a fn to call itself slightly before the event should happen. There's some examples of this in action in the examples directory found within Overtone's source.

Keep it up :-)

We used the external server because I thought it was the only option if you installed the SuperCollider in the Mac Applications directory.

Cool to know about temporal recursion! I will have to check it out. Overtone is very fun. The intersection of technology and art is a very interesting place to explore.