How can I run PHP on JVM (akin to Jython and JRuby)? I am aware of the following:
Quercus, which appears to be dead alive and well.
Seems like I've been visiting the wrong website.
webSphere sMash, that appears to have no documentation
Is there a more mature project for this?
AFAIK, Quercus and P8 are the only two PHP compilers for the JVM, and you already ruled both of them out.
Although I think you are a little bit too harsh: Quercus had its latest release just 23 days ago. Calling it "dead" seems a little premature. And why do you need documentation for P8? The whole point is that it's just PHP. All the documentation you need is right there on PHP.Net.