Re: Scheme function to affect a compound music expression?

[Peter Crighton]

2014-10-24 13:57 GMT+02:00 Peter Crighton <address@hidden>:

2014-10-24 11:05 GMT+02:00 Robin Bannister <address@hidden>:

The source file music-functions.scm defines
music-map
which you can use for this:


bgr = #(define-music-function (parser location music) (ly:music?)
   (music-map (lambda (note)
     #{
       \tweak NoteHead.font-size #-2
       \tweak Accidental.font-size #-2
       #note
     #})
     music ))


There is an advanced example in the regression tests:
http://www.lilypond.org/doc/v2.18/input/regression/collated-files.html#music-map.ly

Thanks a lot, Robin! I wouldn’t have thought it would be this easy …

Although I now came upon the following situation with rests:

\version "2.19.13"

bgr = #(define-music-function

        (parser location music)

        (ly:music?)

        (music-map (lambda (note)

                     #{

                       \tweak NoteHead.font-size #-2

                       \tweak Accidental.font-size #-2

                       #note

                     #})

          music))

\new Voice <<

  \relative c' {

    c4 d r f

  }

  \relative c' \bgr {

    e4 f r a

  }

>>

I get these warnings:

/home/peter/bgr.ly:21:16: warning: Two simultaneous rest events, junking this one

  \relative c' 

               \bgr {

/home/peter/bgr.ly:18:10: warning: Previous rest event here

    c4 d 

         r f

Although it doesn’t seem to affect the output, it is still not desired behaviour, and I don’t know why the \bgr function causes it.

Any ideas?

 

But maybe this could be better documented? I never would have thought of looking for it in the regression tests (in fact I didn’t even know about them).

Are there other places to learn about Scheme in LilyPond than the Scheme tutorial?

--
Peter Crighton | Musician & Music Engraver based in Mainz, Germany
http://www.petercrighton.de