Glenn Morris <rgm@gnu.org> writes:

> It also says:
>
>   It would be straightforward to extend Texinfo to work in a
>   similar fashion for C, Fortran, or other languages.
>
> (All the cool, hip languages!)
>
> The fact that no-one ever bothered, and that @lisp is used a grand total
> of 16 times in the Emacs Lisp Reference manual, indicates to me that
> this feature is... pointless. But YMMV.

dak@lola:/usr/local/tmp/lilypond$ git grep '@lilypond' Documentation|wc -l
9097

And indeed, the @lilypond passages are extracted and compiled separately
as LilyPond code, then the images are reinserted into the output.

With an input like

    @node String number indications
    @unnumberedsubsubsec String number indications

    @cindex string numbers
    @cindex string vs. fingering numbers
    @cindex fingering vs. string numbers

    The string on which a note should be played may be indicated by
    appending @code{\@var{number}} to a note.

    @lilypond[verbatim,quote,relative=0]
    \clef "treble_8"
    c4\5 e\4 g2\3
    <c,\5 e\4 g\3>1
    @end lilypond

    When fingerings and string indications are used together, their
    placement can be controlled by the order in which the two items appear
    in the code @emph{only} if they appear inside of an explicit chord:

generating output like