Help with creating incipit-like custom ambitus

[Spyros Lyberis]

Hi,

I'm currently using lilypond to help my music teacher publish a book of his
lifelong collection of ~100 choir arrangements (both a cappella and
piano-accompanied) and up to now I'm using the normal ambitus grob for the
voice staffs which does the job fine.

However, having worked a lot with older renaissance scores, I'd like to
create a custom ambitus for this book, which resembles the incipits
described in some snippets in the documentation. Specifically:

- For each staff, a new short staff would be created in the instrument
  name, as in the incipits example

- Instead of the starting notes of the music, this short staff must
  contain two notes connected by a glissando: the minimum pitch of
  the actual music of the normal staff, and the maximum pitch.

I think I understand how to do this manually (i.e. finding the min/max
pitches of each staff, and then put these pitches explicitly in the
"incipit"), although I haven't tried it yet. Since we're talking about 100
scores, averaging 400 staffs, the question is: can I write some Scheme
function that AUTOMATICALLY finds the min and max pitches from a ly:music
object?

I've written some simple substitution functions, but I'm still not very
familiar with Scheme. I searched the functions index, but nothing seemed
appropriate. I also looked at ambitus.cc, but that was even more cryptic :)

Can anybody point me to the right direction?


Thanks in advance,
Spyros