This is really awesome, and at its core a powerful concept. After checking the diva out, a thought occurred to me: any new language revision should come with an officially supported tool from the authors to translate changes backwards.

Counter to the logic of tools like Python's 2to3, I think the more important need is to start writing new code, not porting old code. If you can run new code on the old runtime / interpreter / whatever, you get all the good feels. Porting sucks. New features rock. It just seems like a far superior experience for everyone involved. If happiness is how infomemes spread, assuaging the porting woes couldn't hurt.

I realize there could be concerns involving performance, changes to semantics, etc. that may make back-transliterated (transpiled?) code inherently worse. But if language designers took design of a backwards compiler into consideration when writing the new grammar and semantics, we might see smaller changes brought about in an overall faster pace of iteration.

Just a thought.

This tool is neat. :)