Hi all,
Am 09.11.22 um 16:11 schrieb David Kastrup:
<https://lilypond.org/doc/v2.23/Documentation/notation/writing-rhythms#scaling-durations>
says:
Factors may also be added by using Scheme expressions evaluating to a
number or musical length like `*#(ly:music-length music)`.
Is there an example of such addition handy?
The stripped-down example below works, but `\after 8*9' would be
better written `\after #( <something involving 2. and 4.> )`.
The best I could glean from the documentation looks something like:
\after #(ly:moment-add (ly:make-duration 2 1) (ly:make-duration 4 1))
... except that yields a type error because I’m creating durations not
moments.
Maybe something like
\after #(make-duration-of-length (ly:music-length #{ 2. 4. #}))
Or, with a bit of added sugar:
\version "2.23.4"
duration =
#(define-scheme-function (mus) (ly:music?)
(make-duration-of-length (ly:music-length mus)))
{
\after \duration { 2 8 } ->
\repeat unfold 16 { 8 }
}
Arguably it would make sense for \after to just accept example music as
the delay specification.
I thought along the same lines, but seeing as
{
\after \duration 2 ->
\repeat unfold 16 { 8 }
}
does not work, I'm not sure that would be easy - and of course we have
the ambiguity with respect to { 2-> }.
So it doesn't seem like we can just let after expect ly:music? for the
duration. I'm a bit surprised that
\version "2.23.4"
#(define (duration-or-music? x)
(or (ly:duration? x) (ly:music? x)))
duration =
#(define-scheme-function (x) (duration-or-music?)
(if (ly:duration? x)
x
(make-duration-of-length (ly:music-length x))))
{
\after \duration 2. ->
\repeat unfold 16 { 8 }
}
actually seems to work, but to me it looks kind of fishy...
Lukas
