Simple Chord Progression Map

chord.clj

;; http://mugglinworks.com/chordmapsArchive/images/map1.gif
;; http://mugglinworks.com/chordmapsArchive/part3.htm
;;
;; To use the map, remember two things. 
;;   First, you may jump anywhere from I. 
;;   Second, if a chord appears at more than one place, there is an "imaginary tunnel" 
;;     connecting both spots, so you can move from one to the other.
;;
;; reddit discussion 
;; http://www.reddit.com/r/WeAreTheMusicMakers/comments/2g3p7a/chord_progression_map_pick_a_key_and_play_a_chord/
;;
{ :I   {:ii :iii :IV :V :vi} ;; start here
  :ii  {:iii :V}
  :iii {:IV :vi}
  :IV  {:I :ii :V}
  :V   {:I :iii :vi}
  :vi  {:ii :IV}
  ;; :vii (I wonder where this is?)
}