Cross-language compilers aren't a particularly new concept, though. And I fail to see how this one's exactly useful, either. Seems more like an "it can be done" sort of challenge, rather than a tool people would use in everyday programming.

But since it's currently the #1 post on Hacker News, maybe people do have some use for a Ruby-to-Java compiler, so could you enlighten me?

See http://stackoverflow.com/questions/12487986/how-can-i-make-r... . The tl;dr of it is that MRI is atrocious at memory management. For political reasons we are stuck using Ruby in a situation like that; if we could easily, accurately compile that to Java and run it with with java -jar my_script.jar it'd be awesome.

You are aware of JRuby, no?

And just for anyone unaware, this project is by the author of JRuby.

Just for the sake of correctness, Charles Oliver Nutter is actually of one of the main developers of JRuby, a project created about 10 years ago but which has evolved a LOT since then. See http://en.wikipedia.org/wiki/JRuby#History

I am aware, but I haven't really had the time to get involved in testing it. I know we'd have to make some code changes because we depend on modules with native extensions in our script, but I don't know that they'd really be prohibitive.

Much easier would be: "Make this Java with one command to a cross-compiler".

Thanks, I figured there would be some situation like this that'd inspire one to write a cross compiler.

Think of this as art - it doesn't need to have a purpose.

Or think of it as the solution to a problem yet to be discovered - isn't that how most discoveries are made?

Either way great achievement.

It is a feat of compiler design if it works even adequately. I was expecting to see some example output, though.

I'll try to add some for you tonight :-)

Cross-language compilers are not a new concept, you're right about that. I was more enthusiastic about the fact that any person trying to offer alternatives is doing a good deed.

Whether or not this has practical applications is irrelevant for now, the project seems to be in its infancy. Nonetheless, it's a good thing that the author is trying and tackling new concepts.