Re: arbitrary repeat counter

[Jean Abou Samra]

Le 01/06/2022 à 18:19, Simon Bailey a écrit :
> Hi,
>
> On Wed, 1 Jun 2022 at 17:09, Jean Abou Samra - jean at abou-samra.fr
> <mailforwards@cloudmails.net> wrote:
> > What did not work? This is perfectly valid Scheme:
> >
> > (set! count (1+ count))
> (set! counter (+ counter 1))
>
> was giving an error message. Probably had some misaligned parentheses
> or other weirdness. I didn't know about (1+ var) ;)
>
> > You're welcome. To be honest, and simplifying a bit, I had a
> > year of unsuccessful attempts to grasp Scheme before Urs'
> > Scheme tutorial made me learn as much of Scheme in 4 hours
> > as I had learnt in a year, then another year without that kind
> > of help to learn LilyPond internals, so if I've managed to write
> > something that is similarly turning a year into 4 hours for
> > you, I'm quite happy.
> Your readthedocs thing really helped; I still need to have a look at
> Urs' tutorial. I did some functional programming sometime at the
> beginning of the millenium, but 20yrs of OOP is a hard habit to break
> ;-)


For what it's worth, while LilyPond's seldom uses it, Guile actually
has an object-oriented layer.

https://www.gnu.org/software/guile/manual/html_node/GOOPS.html

You may find yourself liking that. This shows that OOP is or
can be largely orthogonal to functional vs. imperative.



> A further definition:
>
> repeatCountingWithTags = #(define-music-function (n music) (index? ly:music?)
>    #{
>      <<
>        \tag #'score \repeat unfold #n { #music }
>        \tag #'part \repeatCounting #n { #music \bar "!|" }
>      >>
>    #})
>
> ebass = \relative c {
>    \clef bass
>    \time 7/4
>    \repeatCountingWithTags 4 { c4. 8 r4 8 r c2. | d4. 4. 4 e2. | 1 r2 r4 | }
> }
>
> \new StaffGroup <<
>    \new Staff \with { instrumentName = "Score" } \keepWithTag #'score \ebass
>    \new Staff \with { instrumentName = "Part" } \keepWithTag #'part \ebass
> and I get the attached output, which is exactly what I want. And it
> makes my input files so much easier to read and manage.
>
> Thanks ever so much for your help!



Again, you're welcome.

Best,
Jean