Re: flats as sharps and sharp as flats

[Stefan Thomas]

Dear community,
with Your hints I made success with my idea of changing the enharmonic context.
But, what I did doesn't still work like I expect it.

Here is an example with short comments on it:

\version "2.13.0"
#(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 (eq? n 6) (eq? n 2)))
      (set! a (- a 2))
      (set! n (+ n 1)))
     ((and (< a -1) (or (eq? n 0) (eq? 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 (lambda (x) (naturalize x)) 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 (parser location m)
                                        (ly:music?)
                        (naturalize m))
%shows only sharps

showSharps = #(define-music-function (parser location x) (ly:music?)
     #{
          \naturalizeMusic  \transpose  ges fis  $x
     #})
%show only flats
showFlats = #(define-music-function (parser location x) (ly:music?)
     #{
          \naturalizeMusic  \transpose  fis ges  $x
     #})
scale = \relative c' {
c4 cis d dis e f fis g gis a ais b c b bes a aes g ges f e es d des
}
\new Staff {
\showSharps    {\scale } %this works fine!
\showSharps { \transpose c e \scale } %why it shows "eis", and not "f"?
}