Re: concatenating notes with a music expression

[Gianmaria Lari]

On 15 May 2018 at 12:10, David Kastrup <address@hidden> wrote:

Malte Meyn <address@hidden> writes:

> Am 15.05.2018 um 10:27 schrieb Gianmaria Lari:
>> Thank you Gilles!!!! I have yet a problem, how can engrave the foo
>> generated list in a score?
>
> You should make a music-function:
>
> \version "2.19.81"
>
> foo =
> #(define-music-function (seq1 seq2) (ly:music? ly:music?)
>    (make-sequential-music
>     (map (lambda (note)
>            (make-sequential-music
>             (cons note (ly:music-property seq2 'elements))))
>       (ly:music-property seq1 'elements))))
>
> seqI = { c b a }
> seqII = { f g }
>
> \foo \seqI \seqII

Nope.  You need to write

(ly:music-deep-copy (ly:music-property seq2 'elements))

instead of
(ly:music-property seq2 'elements)

here or you'll get surprising results whenever the result is changed in
place (like when transposing the result).

Incidentally, it might make sense to write instead

foo =
#(define-music-function (seq1 seq2) (ly:music? ly:music?)
  (set! (ly:music-properties seq1 'elements)
    (map! (lambda (note)
      (music-clone seq2
      'elements (cons note (music-clone (ly:music-property seq2 'elements)))))
      (ly:music-property seq1 'elements)))
  seq1)

That will take the structure of the respective sequences as templates,
so you can use <<...>> instead of {...} for either and have this
reflected in the result.  Also <...> though that will make sense only
for the inner structure.

David I copied and pasted you code but it didn't compile. I changed ly:music-properties to ly:music-property but it doesn't compile anyway. 

This is the complete code:

\version "2.19.81"

foo =

#(define-music-function (seq1 seq2) (ly:music? ly:music?)

  (set! (ly:music-property seq1 'elements)

    (map! (lambda (note)

      (music-clone seq2

      'elements (cons note (music-clone (ly:music-property seq2 'elements)))))

      (ly:music-property seq1 'elements)))

  seq1)

seqI = { c b a }

seqII = { f g }

{\foo \seqI \seqII}

... and this is the error I get

Starting lilypond-windows.exe 2.19.81 [Untitled (9)]...

Processing `C:/Users/GIANMA~1/AppData/Local/Temp/frescobaldi-f2cfs6t1/tmpj6o5qsf6/document.ly'

Parsing...C:/Program Files (x86)/LilyPond/usr/share/lilypond/current/scm/music-functions.scm:1063:31: In procedure ly:music-mutable-properties in _expression_ (ly:music-mutable-properties music):

C:/Program Files (x86)/LilyPond/usr/share/lilypond/current/scm/music-functions.scm:1063:31: Wrong type argument in position 1 (expecting Prob): (#<Prob: Music C++: Music((pitch . #<Pitch f >) (duration . #<Duration 4 >) (origin . #<location C:/Users/GIANMA~1/AppData/Local/Temp/frescobaldi-f2cfs6t1/tmpj6o5qsf6/document.ly:12:11>))((display-methods #<procedure #f (note)>) (name . NoteEvent) (iterator-ctor . #<primitive-procedure ly:rhythmic-music-iterator::constructor>) (types event note-event rhythmic-event melodic-event)) >

#<Prob: Music C++: Music((pitch . #<Pitch g >) (duration . #<Duration 4 >) (origin . #<location C:/Users/GIANMA~1/AppData/Local/Temp/frescobaldi-f2cfs6t1/tmpj6o5qsf6/document.ly:12:13>))((display-methods #<procedure #f (note)>) (name . NoteEvent) (iterator-ctor . #<primitive-procedure ly:rhythmic-music-iterator::constructor>) (types event note-event rhythmic-event melodic-event)) >

)

Exited with return code 1.

g.