Thank you Jan, very clear.
g.
On Tue, 27 Nov 2018 at 11:48, Jan-Peter Voigt <jp.vo...@gmx.de> wrote:
> Hello,
>
> the $ sign has a special meaning of "instant scheme-expression". An
> instant scheme expression is evaluated instantly *and* the result is
> observed so that lilypond can decide what to do with it. When lily
> receives something that can be treated as a markup from an instant
> scheme expression it is handled like \markup {}. But a pure string is
> not a core lily-expression like music or markup. Thats the reason (3)
> fails with an error. The result of a plain scheme-exression introduced
> with # is simply ignored in root context.
>
> HTH
> Jan-Peter
>
>
> Am 27.11.18 um 09:14 schrieb Gianmaria Lari:
> > Probably these are very trivial things. Sorry to ask them but would like
> > to understand.
> >
> > If I write (1):
> >
> >
> > \version "2.19.82"
> > $(object->string (+ 3 2))
> >
> >
> > Lilypond is happy and compile to a pdf file showing "5".
> >
> > Even this simpler code works... (2)
> >
> > \version "2.19.82"
> > $"Hello"
> >
> >
> > and generate a pdf file showing "Hello".
> >
> > It is clear to me that $ introduce a scheme expression that is
> > evaluated. And in the previous two examples the scheme code is evaluated
> > to strings. But I don't understand why lilypond outputs them. If I write
> > (3):
> >
> > \version "2.19.82"
> > "Test"
> >
> >
> > this does not compile. So I would think that the "correct" code to
> > output evaluated expression in the pdf file should be (4)
> >
> >
> > \version "2.19.82"
> > \markup $(object->string (+ 3 2))
> >
> >
> > or this (5)
> >
> > \version "2.19.82"
> > \markup $"Hello"
> >
> >
> > Why the behaviour of (1) and (2) ?
> >
> > * * *
> >
> > I tried to rewrite (1) and (2) with the hash mark instead of dollar (6):
> >
> > \version "2.19.82"
> > #(object->string (+ 3 2))
> >
> >
> > and (7):
> >
> > \version "2.19.82"
> > #"Hello"
> >
> >
> > This time, there is no output in the pdf file. Why this difference?
> >
> > Thank you, g.
> >
> > _______________________________________________
> > lilypond-user mailing list
> > lilypond-user@gnu.org
> > https://lists.gnu.org/mailman/listinfo/lilypond-user
> >
>
>
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