Automatically convert beams into slurs to indicate melisma

Traditionally, vocal scores used beams to indicate melisma, while modern vocal scores tend to use slurs. With this snippet's \beamsToSlurs music function you can easily produce either type of output from the same music input, allowing you to have both traditional and modern vocal engraving with one unique source. The function automatically converts manually typeset beams: [ ] ...into slurs: ( ).

\version "2.24"

% a music function to convert manually typeset beams: [ ] ...into slurs: ( )

beamsToSlurs =
#(define-music-function (music) (ly:music?)
   (music-map
     (lambda (m)
       (if (not (null? (ly:music-property m 'articulations)))
           (for-each
             (lambda (a)
               (if (music-is-of-type? a 'beam-event)
                   (begin
                    (ly:music-set-property! a 'name 'SlurEvent)
                    (ly:music-set-property! a 'types
                      (append
                       (delete 'beam-event (ly:music-property a 'types))
                       '(slur-event)))
                    (ly:music-set-property! a 'spanner-id ""))))
             (ly:music-property m 'articulations))
             m)
       m)
     music))

%%%%%%%%%%%%%%%%%%%%%%%%%

music = {
  \time 2/4
  | c'8[ d'] e' f'
  | g'[ a'] b' c''
}

words = \lyricmode {
  la li lo 
  la li lo
}

<<
  \new Staff \with { instrumentName = "Traditional" } 
    { \autoBeamOff \music }
    \addlyrics \words
  
  \new Staff \with { instrumentName = "Modern" }
    \beamsToSlurs \music
    \addlyrics \words
>>