Tricky repeat structure for "32-bar form" AABA

[Joel C. Salomon]

If I understand correctly, a volta repeat within a D.C. repeat is only supposed to play the first time.  I’ve worked out how to accomplish this in the presence of `\unfoldRepeats` (as useful for MIDI creation) in the context of a “thirty-two-bar form”, or AABA-form, song.  Might be useful to others.

Comments (even of the “no, don’t do that, and here’s why” sort) are welcome.

Fun thing is, replacing the hard-coded `\after 1*8` with `\after \duration \A` (using Lukas’s `\duration` from <https://lists.gnu.org/archive/html/lilypond-user/2022-11/msg00092.html>) also works, so one could possibly turn this into a function that takes two music arguments.

—Joel

\version "2.24.0"

A = {
  \repeat unfold 8 { a'4 a' a' a' | }
  \section
}

B = {

  \repeat unfold 8 { b'2 b' | }
  \section
}

AABA = {
  \repeat segno 2 {
    \volta #'() {
      \volta 2 \after 1*8 \fine
      \repeat volta 2 \A
    }
    \unfolded {
      \volta 1 \repeat volta 2 \A
      \volta 2 { \A \fine }
    }
    \volta 1 \B
  }
}

\score {
  \AABA
}

\score {
  \unfoldRepeats \AABA
}