\paper { tagline = ##f }

#(define-public (extended-dynamic-absolute-volume s)
     (cond
      ((string? s )
       (default-dynamic-absolute-volume s))
      ((rational? s)
       (exact->inexact s))
      ((number? s )
       s)
      (else throw "this will never happen" )))

vel = #(define-event-function (velocity)(number?)
            (make-music 'AbsoluteDynamicEvent 'text velocity 'direction 1)
           )

sin-wave = #(define-scheme-function () ()
            (define frequency 512)
            (define loop-length 512)
            (make-music 'SequentialMusic
                'elements
                (let loop ((counter 0 ))
                    (let ((v
                           (+ (/ (sin (* PI
                                          (/ counter
                                              (/ frequency 32))))
                                  2 )
                               0.5 )))

                      (let (( v (if (< counter loop-length )
                                  (cons
                                    (make-music 'NoteEvent
                                                'pitch
                                                (ly:make-pitch 1 0 0 )
                                                'duration
                                                (ly:make-duration 8 0 1 )
                                                'articulations
                                                (list (make-music
                                                        'AbsoluteDynamicEvent
                                                        'tweaks '((stencil ()))
                                                        'direction
                                                        -1
                                                        'text
                                                        v ))
                                                )
                                    (loop (+ counter 1)))

                                  '())))
                        (if (= (modulo counter 64) 0 )
                          (append
                            (list
                              (make-music
                                'ContextSpeccedMusic
                                'context-type
                                'Timing
                                'element
                                (make-music
                                  'PropertySet
                                  'value
                                  ""
                                  'symbol
                                  'whichBar))
                              (make-music
                                'LineBreakEvent
                                'break-permission
                                'force))
                            v)
                          v))))))
\score {
    <<
        \set Score.dynamicAbsoluteVolumeFunction = #extended-dynamic-absolute-volume
        \sin-wave
    >>
    \layout {
        indent=0
        \context {
            \Score
        }
    }
    \midi {}
}