JPython and Interactive Debugging

[Wilbur Peng]

I am looking around for a script language for my Java application.  I
considered writing a Java VM in Java, but came across JPython some time
ago. Is there any way to interactively debug JPython from _within_ a
Java program?  My 
guess is no, because JPython translates to Java bytecodes, which can be
debugged externally but not "internally".  If this is the case, how
difficult would it be to write an actual Python VM in Java and make it
interoperable with the existing code base?