Generating whole scores (also book parts) in Scheme without using the parser

A LilyPond score internally is just a Scheme expression, generated by the LilyPond parser. Using Scheme, one can also automatically generate a score without an input file. If you have the music expression in Scheme, a score can be generated by simply calling

(scorify-music music)

on your music. This generates a score object, for which you can then set a custom layout block with

(let* ((layout (ly:output-def-clone $defaultlayout)))
   ; modify the layout here, then assign it:
   (ly:score-add-output-def! score layout))

Finally, all you have to do it to pass this score to LilyPond for typesetting. This snippet defines functions (add-score score), (add-text text), and (add-music music) to pass a complete score, some markup, or some music to LilyPond for typesetting.

This snippet also works for typesetting scores inside a \book {...} block as well as top-level scores. To achieve this, each score scheduled for typesetting is appended to the list of top-level scores, and the top-level book handler (which is a Scheme function called to process a book once a \book{...} block is closed) is modified to insert all collected scores so far to the book.

Note: For technical reasons, only the first \book is shown, as the other \book commands create additional output files.

\version "2.24"

% LSR This code was written by Nicolas Sceaux
% LSR (http://nicolas.sceaux.free.fr/)

#(define-public (add-score score)
   (ly:parser-define! 'toplevel-scores
                      (cons score (ly:parser-lookup 'toplevel-scores))))

#(define-public (add-text text)
   (add-score (list text)))

#(define-public (add-music music)
   (collect-music-aux (lambda (score)
                        (add-score score))
                      music))

#(define-public (toplevel-book-handler book)
   (map (lambda (score)
          (ly:book-add-score! book score))
        (reverse! (ly:parser-lookup 'toplevel-scores)))
   (ly:parser-define! 'toplevel-scores (list))
   (print-book-with-defaults book))

#(define-public (book-score-handler book score)
   (add-score score))

#(define-public (book-text-handler book text)
   (add-text text))

#(define-public (book-music-handler book music)
   (add-music music))


% Some example code to show how to use these functions.  Each call to
% `\oneNoteScore` constructs a global markup followed by a single
% staff with a single quarter note.  The pitch of this note is taken
% from the variable `pitch`; the start value 0 corresponds to pitch C.
% After emitting the score, variable `pitch` gets increased by 1.
%
% `\oneNoteScore` calls Scheme function `add-one-note-score` to do all
% the work.

#(define add-one-note-score #f)
#(let ((pitch 0))
   (set! add-one-note-score
         (lambda ()
           (let* ((music
                   (make-music
                    'EventChord
                    'elements (list (make-music
                                     'NoteEvent
                                     'duration (ly:make-duration 2 0 1/1)
                                     'pitch (ly:make-pitch 0 pitch 0)))))
                  (score (scorify-music music))
                  (layout (ly:output-def-clone $defaultlayout))
                  (note-name (case pitch
                               ((0) "do")
                               ((1) "ré")
                               ((2) "mi")
                               ((3) "fa")
                               ((4) "sol")
                               ((5) "la")
                               ((6) "si")
                               (else "huh")))
                  (title (markup #:large #:line
                                 ("Score with a" note-name))))
             (ly:score-add-output-def! score layout)
             (add-text title)
             (add-score score))
           (set! pitch (modulo (1+ pitch) 7)))))

oneNoteScore =
#(define-void-function () ()
   (add-one-note-score))

\book {
  \oneNoteScore

  \paper { tagline = ##f }
}


\book {
  \oneNoteScore
  \oneNoteScore

  \paper { tagline = ##f }
}

% Top-level scores are also handled correctly.
\oneNoteScore
\oneNoteScore

\paper { tagline = ##f }