From my preliminary read of that page and the linked loan.java, it looks like the java is actually being processed into C code and then complied by the server. Can anyone confirm if this is how the system is architected to "support" java?
It does not look like it's running in a normal JRE, which makes me really skeptical of the sibling post claiming that "you can write Java however you want". (If it was running in a normal JRE, a ton of the stuff in loan.java makes little sense...)
I'm not exactly sure how his claims of instant refreshing "scripts" works if it's a conventional JDK, though. I mean, that's just not possible, even with hot reloading (as Play Framework developers have learned to their disappointment).