2012/1/3 David Kastrup <d...@gnu.org>:
> Janek Warchoł <janek.lilyp...@gmail.com> writes:
>
>> 2012/1/3 David Kastrup <d...@gnu.org>:
>
>>> LilyPond needs to get into a state where, say, half the
>>> engravers are written and maintained in Scheme. And by "Scheme" I don't
>>> mean "Scheme at the level Nicolas can barely handle" but "Scheme a
>>> Fortran programmer would not have all too much of a problem
>>> understanding".
>>
>> Umm, impossible? From my perspective, 'Scheme' and 'easy to
>> understand' are mutually exclusive. Unless there are more comments
>> than code - literally - but we don't do so.
>
> Well, as an example, take a look at
> <URL:http://nicolas.sceaux.free.fr/prelude/prelude.html>
Hmm, excuse me while my brain melts ;)
> Now take a look at
>
> \begin{lilypond}
> ph = #(define-music-function (parser location p1 p2 p3 p4 p5)
> (ly:pitch? ly:pitch? ly:pitch? ly:pitch? ly:pitch?)
> #{
> \repeat unfold 2 { $p1 2 } |
> \repeat unfold 2 { r16 $p2 8. ~ $p2 4 } |
> \repeat unfold 2 { r8 $p3 16 $p4 $p5 $p3 $p4 $p5 } |
> #})
> \parallelMusic #'(low middle high)
> {
> \ph c' e' g' c'' e''
> R1*7 | \skip 1*7 | R1*7 |
> \ph a c' e' g' c''
> \voiceTwo | \change Staff = "down" \voiceOne | \oneVoice |
> \ph d a d' fis' c''
> R1*21 | \skip 1*21 | R1*21 |
> \ph c, c g bes e'
> c,2~ c, | r16 c8. ~ c4 ~ c2
> | r8 f16 a c' f' c' a c' a f a f d f d |
> c,2~ c, | r16 b,8. ~ b,4 ~ b,2
> | r8 g'16 b' d'' f'' d'' b' d'' b' g' b' d' f' e' d' |
> c,1\fermata | c1 | <e' g' c''>1\fermata \bar "|." |
> }
> \score {
> \new PianoStaff <<
> \new Staff = "up" {
> << \high \\ \middle >>
> }
> \new Staff = "down" {
> \clef bass
> \low
> }
> >>
>
> \midi {
> \context {
> \Score
> \with \settingsFrom { \tempo 4 = 80 }
> }
> }
>
> \layout {
> \context {
> \Score
> \with \settingsFrom { \compressFullBarRests }
> }
> \context {
> \Staff
> \with \settingsFrom { \accidentalStyle modern }
> }
> }
> }
> \end{lilypond}
>
> \ph is a music function written in Scheme. Can you understand it?
Yes, but i get lost on \parallellMusic :(
> \settingsFrom is actually returning a Scheme expression for \with to
> use. It makes things rather simpler than more complex, even though it
> constitutes a Scheme expression.
Um... i would really love to be able to type
\layout {
\compressFullBarRests
\override Score.SpacingSpanner #'common-shortest-duration =
#(ly:make-moment 6 10)
etc...
}
> Scheme is not hard. Programming is hard. And there is still far too
> much repetitive programming required for stuff that could be handled
> using shrinkwrapped tools (\settingsFrom is such a tool) if anybody had
> bothered packaging them. Far too often if I think "Ok, task x has no
> documented way of dealing with it. Let's see whether we can find an
> undocumented API". And then I find about 10 files implementing their
> own ad hoc API that will break in different ways if one has to change
> the data structures at some point of time.
I agree, this should not work like that.
Janek
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