Here is an IDEA ! Add optional static types support in RPython to provide further compiletime optimizations (along with any type support). This adds static types to Ruby[1] , PHP [2], Python [3] or any dynamic X. I am sure people would pay for enterprise support for this compiler toolchain.
It's the wrong level: the RPython toolchain has no notion of PHP-level types, they're entirely implemented by the interpreter. Besides, optional static types are nearly useless (performance-wise) when you have a JIT.
[1] http://docs.topazruby.com/en/latest/ [2] https://github.com/hippyvm/hippyvm [3] http://pypy.org/