Aaron Hill <lilyp...@hillvisions.com> writes: > On 2020-03-08 3:57 pm, Stephan Schöll wrote: >> It looks as if the "output" (return value) of a function can only be of >> type "music", not "score", "book" aso, which would disappoint me. Am I >> right? Or is there a way to define/change the type of the return value? > > Music functions are for music. Books and scores are not music. > > Scheme functions are capable of returning arbitrary information. > Scores, for instance, can be returned and handled properly. Books > cannot. > > => 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? Without an answer to that question, we cannot implement this. But have you tried explicitly using \book { ... } for getting a book? -- David Kastrup