Splitting chords

This snippet is a 2009 contribution by Gilles Thibault in lilypond-user. It works well in 2.24.4 and even in 2.25.35. I find it very useful. (Beware: it doesn't work if you use «q» to repeat last chord).

\version "2.24"

#(define (has-duration? music)
(ly:duration? (ly:music-property music 'duration)))

#(define (not-has-duration? music)
(not (has-duration? music)))

keepsOnlyFirstNote = #(define-music-function (parser location music) (ly:music?)
(music-map
 (lambda (evt)
  (if (eq? 'EventChord (ly:music-property evt 'name))
     (let ((elts (ly:music-property evt 'elements)))
      (if (has-duration? (car elts))
           (ly:music-set-property! evt 'elements (cons
                (car elts)
                (filter not-has-duration? (cdr elts)))))))
 evt)
music))

deleteFirstNote = #(define-music-function (parser location music) (ly:music?)
(music-map
 (lambda (evt)
  (if (eq? 'EventChord (ly:music-property evt 'name))
     (let ((elts (ly:music-property evt 'elements)))
          (if (has-duration? (car elts))
               (ly:music-set-property! evt 'elements  (cdr elts)))))
 evt)
music))


music =\relative c' {
<c e>4-> <d f>( <b g'>) <c e>-. g2 c2
}

\markup { Music with chords }
\new Staff \music
\markup { Music splitted in 2 staffs }
<<
  \new Staff \deleteFirstNote \music
  \new Staff \keepsOnlyFirstNote \music
>>