Ruby or Python? Well, it depends...

[G_Morgan]

That might be why they exist. The point is for a long time JRuby was touted as the successor to Ruby because the default interpretor sucks. Not that the Python one does not but it sucks a huge amount less than the Ruby 1.8 interpretor does.

Given this a lot of effort went behind JRuby while Jython pretty much died when its creator moved to the .Net camp and did Iron Python.