My first Overtone piece: the most simplistic 12-tone variant.

12-tone.clj

(ns overtrial
  (:use [overtone.live]
        [overtone.inst.piano]
        [overtone.inst.sampled-piano]))

(defonce metro (metronome 120))

(defn play-12-loop
  [m beat-num tone-row tone-buf]
  (if (empty? tone-buf)
    (play-12-loop m beat-num tone-row tone-row)
    (do
      (at (m (+ 0.25 beat-num)) (sampled-piano (note (first tone-buf))))
      (apply-at (m (+ 0.25 beat-num))
                play-12-loop
                m
                (+ 0.25 beat-num)
                tone-row
                (rest tone-buf)
                []))))

(defn play-12-tone
  ([m beat-num]
     (play-12-tone m beat-num [:C4 :C#4 :D4 :D#4 :E4 :F4 :F#4 :G4 :G#4 :A4
                               :A#4 :B4] []))
  ([m beat-num genesis-row tone-row]
     (if (empty? genesis-row)
       (apply-at (m (+ 0.25 beat-num))
                 play-12-loop
                 m
                 (+ 0.25 beat-num)
                 tone-row
                 []
                 [])
       (let [current-note (choose genesis-row)]
         (at (m (+ 0.25 beat-num)) (sampled-piano (note current-note)))
         (apply-at (m (+ 0.25 beat-num))
                   play-12-tone
                   m
                   (+ 0.25 beat-num)
                   (remove (fn [a-note] (= a-note current-note)) genesis-row)
                   (conj tone-row current-note) [])))))
(play-12-tone metro (metro))
(stop)