Using Lilypond as a Lilypond preprocessor.

[Darius Blasband]

Hi,

I think it might be a good idea for Lilypond to provide a facility 
which, based on an input file, provides
a normalized intermediate file which is itself a valid Lilypond file, 
with exactly the same semantics as the
original one, but where the variables (or at least, the user-define 
ones) are expanded, all pitches and
note durations are set to their absolute value, etc...

This file would definitely not be meant to be edited, but would be used 
for further processings. Since it is
much simpler than a plain Lilypond file, reading it would be much 
simpler. Since all pitches and note
durations are set explicitly, there is no room for misunderstanding.

For instance one might consider rewriting the MIDI generator based on 
this intermediate file
(and allow for the current implementation to be phased out, as no one 
wants to work at it, and
as it seems to deal with excessively complex data structures), or a 
Midge generator, or a MusicXML
export, or even a Finale Export (ok, ok, just kidding... :-) )

Since this intermediate file is a valid Lilypond file, an intermediate 
pass can perform some kind of transformation
on it before passing it back to Lilypond for actual processing.

Is this reasonable ? or is Lilypond's internal data structure too 
complex for this to be feasible ?

Cheers,

Darius.