=> David K., do you know why the parser balks at such a top-level
ly:book?
How can a book be distinguished from a bookpart?
Are they both ly:book? behind the scenes? If so, I can see the problem.
Without an answer to
that question, we cannot implement this. But have you tried explicitly
using
\book { ... }
for getting a book?
I suspect I am misunderstanding you. Here is what else I have tried:
%%%%
\version "2.20"
bookFunc = #(define-scheme-function () ()
#{ \book { \score { { b'4 } } } #})
% \bookFunc % fails - bad expression type
% \book { \bookFunc } % fails - bad expression type
$#{ \bookFunc #} % works?!
%%%%
-- Aaron Hill
