Combining Java with other languages

How often is language choice dictated by the availability of existing libraries? For me, quite often! I have been looking at two approaches to leveraging Java code for alternative languages/platforms:

• IKVM - a JVM implementation (uses GNU CLASSPATH) that runs inside Mono and Microsoft's .Net CLRs

• PyLucene - the large Java Lucene search application is compiled using GNU gcj into native code and then wrapped using SWIG as a Python library

I have used PyLucene with Python: great to be able to effectively use a large Java application in Python. I have not experimented with IKVM yet, but for a practical Java programmer who might need to reuse some code in the .Net framework: it looks promising.