There is an ever-growing list of languages available for software development, with so many new ones popping up that sometimes you really have to ask why?
Most seem to claim to be more expressive for certain things, easier to use, or more portable.
Entraspan is heavily committed to the Java programming language, but often times will experiment with other languages.
Bottom line from experience is that programming in the large with 100 K lines of code or more is best done with compiled languages that do strong type checking and call syntax checking at compile time.
Interpreted languages should be restricted to small programs or cases where they bring a true advantage or maybe the only one that will work with certain products.
The reason boils down to cost. The development cost can be similar, but the real costs come in over the software life-cycle when dramatic refactoring needs to be made to adapt to different requirements. Compiled languages will catch many problems at compile time. Interpreted languages require a rigorous set of test cases which must be run to try to catch as many as possible followed by extensive test & evaluation to find the remaining problems.
Many of the techniques used and the technology developed by Entraspan has been to attain the maximum leverage of the languages used to be able to quickly build and refactor software that has 100's of thousands of lines of source and databases that contain 100's of tables.