2012/6/11 Matthew Probst <matt...@yak.org>: > I understand the Scheme language at intermediate level, but am not adept at > processing Lilypond data structures. > > I'm looking into Snippet 465: > > http://lsr.dsi.unimi.it/LSR/Item?id=465 > > I have the following in my Lilypond code, for typesetting a common guitar > strum pattern: > > rhtOne = #(rhythm-template #{ s16 s16 r8 s16 #} ) > \relative c' { r4 \rhtOne <f a d>1 r2 } > > This works fine. However, this does not: > > rhtOne = #(rhythm-template #{ s16 s16 r8 s16 #} ) > Dnine = { \relative c' { <f a d>1 } } > \relative c' { r4 \rhtOne \Dnine r2 } > > > The problem is that the snippet constructs a single chord event to apply the > rythm to, by walking down the 'elements property of the first parameter, and > collecting their pitches into a list with (map): > > http://pastebin.com/tSm1tw65 > > The data structure this sees from my first Lilypond example is like this: > > http://pastebin.com/Tx8qhz6u > > > However, the data structure created by my second Lilypond example looks more > like this: > > > http://pastebin.com/FuCRHDyK > > > In the first example, it sees an 'EventChord, so we properly fetch a list of > all its children's 'pitch properties. In the second example, it's > 'SequentialMusic, not an 'EventChord. What I want to do is walk down the > data structure and find the first EventChord or NoteEvent. > > > That doesn't seem too hard, actually. Need to define a function > first-non-sequence, and conditionally drill farther into the data structure > until I find the first non-sequence. Understanding that this is pseudocode > instead of proper syntax, I'd need to do something roughly like the > following: > > > http://pastebin.com/3eNNYjHE > > > Also have to potentially recurse farther into nested levels of > 'SequentialMusic or down each item in the 'elements list, I am comfortable > fleshing it out to that level. > > > What I'm wondering, is what (if any) Lilypond scheme function do I use to > determine the type of a music data structure? I could certainly just say > (car mus) but I'm wondering if there's a function I should use for the sake > of encapsulation. I see that one can get properties of a music element with > (ly:music-property mus 'SYMBOL), the existing snippet code grabs the > 'elements list using (ly:music-property mus 'elements).
try (ly:music-property mus 'name) I think that does it? Jakob. > > > If it's just a matter of use (car mus) and comparing the symbol against a > given list of options, fine, I just don't know if I'm going the right way. > I've been looking at the docs for several days now, and have done so at > several times in the past, and I'm just not quickly finding what I need. > > > My goal is to finally immerse myself into the Scheme side of Lilypond, and > start implementing some fixes to the various rhythm-pitch template snippets > that I've been wishing for, instead of complaining. > > > _______________________________________________ > lilypond-user mailing list > lilypond-user@gnu.org > https://lists.gnu.org/mailman/listinfo/lilypond-user > _______________________________________________ lilypond-user mailing list lilypond-user@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-user
