(in-package :cm)
(in-syntax :midi)

;;;
;;; Example of the rewrite pattern.  Uses same grammer as Tom Johnson in
;;; his piece "Formulas for String Quartet": given alphabet {+ -}, rewrite + 
;;; with + - + and rewrite - with - - +.  In our example we use a step
;;; stream where + is defined as a whole step up and - is a whole step down.
;;; use a quartet of voices spaced 5th apart in different tempi.
;;;

(merge tj ()
  (loop with tempo = 100
        for r in '(16 8 4 2)
        for n in '(c5 f4 bf3 ef3)
        do
    (let ((r (rhythm r tempo))
          (n n))
    (algorithm nil midi-note (note n amplitude .4 end 20
                              rhythm r duration r)
      (vars (s (steps (2 to (2 -2 2)) (-2 to (-2 -2 2))
                      in rewrite initially 2 initially-from note)))
      (setf note (item s))))))

#|
write tj test.midi 0
|#