+\version "2.19.22"
+
+\header {
+ lsrtags = "pitches, scheme-language, workaround"
+
+ texidoc = "
+This example uses some Scheme code to enforce enharmonic modifications
+for notes in order to have the minimum number of accidentals. In this
+case, the following rules apply:
+
+Double accidentals should be removed
+
+
+B sharp -> C
+
+
+E sharp -> F
+
+
+C flat -> B
+
+
+F flat -> E
+
+
+In this manner, the most natural enharmonic notes are chosen.
+
+"
+ doctitle = "Transposing pitches with minimum accidentals (\"Smart\" transpose)"
+}
+#(define (naturalize-pitch p)
+ (let ((o (ly:pitch-octave p))
+ (a (* 4 (ly:pitch-alteration p)))
+ ;; alteration, a, in quarter tone steps,
+ ;; for historical reasons
+ (n (ly:pitch-notename p)))
+ (cond
+ ((and (> a 1) (or (eqv? n 6) (eqv? n 2)))
+ (set! a (- a 2))
+ (set! n (+ n 1)))
+ ((and (< a -1) (or (eqv? n 0) (eqv? n 3)))
+ (set! a (+ a 2))
+ (set! n (- n 1))))
+ (cond
+ ((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
+ ((< a -2) (set! a (+ a 4)) (set! n (- n 1))))
+ (if (< n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
+ (if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
+ (ly:make-pitch o n (/ a 4))))
+
+#(define (naturalize music)
+ (let ((es (ly:music-property music 'elements))
+ (e (ly:music-property music 'element))
+ (p (ly:music-property music 'pitch)))
+ (if (pair? es)
+ (ly:music-set-property!
+ music 'elements
+ (map naturalize es)))
+ (if (ly:music? e)
+ (ly:music-set-property!
+ music 'element
+ (naturalize e)))
+ (if (ly:pitch? p)
+ (begin
+ (set! p (naturalize-pitch p))
+ (ly:music-set-property! music 'pitch p)))
+ music))
+
+naturalizeMusic =
+#(define-music-function (m)
+ (ly:music?)
+ (naturalize m))
+
+music = \relative c' { c4 d e g }
+
+\score {
+ \new Staff {
+ \transpose c ais { \music }
+ \naturalizeMusic \transpose c ais { \music }
+ \transpose c deses { \music }
+ \naturalizeMusic \transpose c deses { \music }
+ }
+ \layout { }
+}