lilypond-common-includes/swing_style.ly

swing = \mark \markup {
  \line \general-align #Y #DOWN {
    \score {
      \new Staff \with {
        fontSize = #-2
        \override StaffSymbol.line-count = #0
%        \override VerticalAxisGroup.Y-extent = #'(0 . 0)
      }
      \relative {
        \stemUp
        \override Score.SpacingSpanner.common-shortest-duration = #(ly:make-moment 3 16)
        \override Beam.positions = #'(2 . 2)
        h'8[ h8]
      }
      \layout {
        ragged-right= ##t
        indent = 0
        \context {
          \Staff \remove "Clef_engraver"
          \remove "Time_signature_engraver"
        }
      }
    }
    " ="
    \score {
      \new Staff \with {
        fontSize = #-2
        \override StaffSymbol.line-count = #0
%        \override VerticalAxisGroup.Y-extent = #'(0 . 0)
      }
      \relative {
        \stemUp
        \override Score.SpacingSpanner.common-shortest-duration = #(ly:make-moment 3 16)
        \override Stem.length = #4.5
        \tuplet 3/2 { h'4 h8 }
      }
      \layout {
        ragged-right= ##t
        indent = 0
        \context {
          \Staff
          \remove "Clef_engraver"
          \remove "Time_signature_engraver"
        }
      }
    }
  }
}

\include "swing.ly"

swingMusic =
#(define-music-function (parser location music) (ly:music?)
  (define (partial-duration-length m)
    (let ((name (ly:music-property m 'name))
          (es (ly:music-property m 'elements))
          (e (ly:music-property m 'element)))
      (if (pair? es)
        (partial-duration-length (car es))
        (if (ly:music? e)
          (if (and (eq? name 'ContextSpeccedMusic) (eq? (ly:music-property e 'name) 'PartialSet))
            (ly:duration-length (ly:music-property e 'duration))
            (if (eq? name 'NoteEvent)
              ZERO-MOMENT
              (partial-duration-length e)
            )
          )
          ZERO-MOMENT))))
#{
  \swing
  \applySwingWithOffset 8 #'(2 1) #(partial-duration-length music) #music
#})