From: Steve Whalen on
The good news about BUSH (besides being written mostly in Ada) is that
it's license is GPL / GMGPL.

It doesn't seem to be receiving much work from Pegasoft, so if you
wanted, you could "fork" the project and fix the problems you see and
add enhancements, if you have the time.

I haven't looked at the source enough to see if it would benefit
significantly from the new features in Ada 200X, but now that Ada has
it's version of "downward closure" maybe that would make it easier to
implement your "shell" downward closure (which I'm not sure I
understood, but I'm sure that's because I haven't had time to really
think about it).

Steve