Re: Scheme function to affect a compound music expression?

[Simon Albrecht]

Hello all,

I tried to write such a function, but failed at the point you’ll see in the attachment. I’d like to learn how this can be made to work ;-) … The problem is in extracting the list from SequentialMusic’s 'element property. And I suspect it has to do with the following question:
With display-music I can obtain:
#<Prob: Music C++: Music((duration . #<Duration 4 >) (pitch . #<Pitch e >) (origin . #<location c:/users/simon/appdata/local/temp/frescobaldi-_4tllv/tmpdndxnp/bgr.ly:25:10>))((display-methods #<procedure #f (note parser)>) (name . NoteEvent) (iterator-ctor . #<primitive-procedure ly:rhythmic-music-iterator::constructor>) (types general-music event note-event rhythmic-event melodic-event)) >

: { ((duration . #<Duration 4 >) (pitch . #<Pitch e >) (origin . #<location c:/users/simon/appdata/local/temp/frescobaldi-_4tllv/tmpdndxnp/bgr.ly:25:10>)) }
and with display-scheme-music:
(make-music

'NoteEvent

'duration

(ly:make-duration 2)

'pitch

(ly:make-pitch -1 2))
What kind of syntax is the first one? And how can I compute one from the other?

Grateful as always for help and with best regards,
Simon

Am 23.10.2014 um 14:05 schrieb Peter Crighton:

Hello all,

I’m taking my very first little steps into Scheme right now by trying to write a function that can make single note heads (and accidentals) in a chord smaller (to differentiate background vocals from lead vocal when writing them all in one voice).

What I have so far is:

bgr = #(define-music-function

        (parser location note)

        (ly:music?)

        #{

          \tweak NoteHead.font-size #-2

          \tweak Accidental.font-size #-2

          #note

        #})

or

bgr = #(define-music-function

         (parser location note)

         (ly:music?)

         (set! (ly:music-property note 'tweaks)

               (cons (cons (cons (quote NoteHead) (quote font-size))

                       -2)

                 (ly:music-property note 'tweaks)))

         (set! (ly:music-property note 'tweaks)

               (cons (cons (cons (quote Accidental) (quote font-size))

                       -2)

                 (ly:music-property note 'tweaks)))

         note)

which should be the same.

Here is an example that uses it:

\new Voice <<

  \relative c' {

    c4 d e f

  }

  \relative c' {

    \bgr e4

    \bgr f

    \bgr g

    \bgr a

  }

>>

But I would like to be able to use the function as follows, so it doesn’t only affect the next note, but a sequence of notes enclosed in { … }:

\new Voice <<

  \relative c' {

    c4 d e f

  }

  \relative c' {

    \bgr { e4 f g a }

  }

>>

Can somebody point me in the right direction how to do this?

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

_______________________________________________
lilypond-user mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/lilypond-user

bgr.ly
Description: Text Data