While technically your statement is true - HHVM had zero ground some time ago and standard PHP had 100% ground, and now HHVM has some ground (which is witnessed by your use of it) so PHP has less than 100% - the substance of it - implying that HHVM is somehow fast on its way to replace PHP - does not match observed reality. Extraordinary claims require extraordinary proof, and so far none was provided. It is great to see this project gaining acceptance, but let's not get ahead of the facts and claim something that does not exist yet.
Nobody cares about today; everybody cares about tomorrow. If you've closely monitored the developments around HHVM and applied knowledge from past experience with successfully managed projects, you'd have zero doubt that HHVM has all components of being widely successful. It will never reach 100%, but for larger projects, it will be preferred just like many go thru the trouble of implementing Nginx + PHP-FPM vs stock Apache + mod_php.
a) it's run developed by a company whose policy is "move fast and break things". I have seen the result of this mantra first hand in their fucking terrible Facebook "api" where something breaks every time anyone anywhere in the world farts.
b) the number and nature of incompatibilities are too vast.
c) their intention is pretty clear with "hack" - they want a php-like language but not php. That's fine they can do that but I won't use it.
The mantra is changing (as of this f8). There's nothing wrong with evolving PHP or any language. Being stalled for so long gave other languages a chance to steal from its pie, but there are signs (like with phpng) that things are changing. Java was stubborn enough not to evolve for so long, but even they learned already. Everybody is doing rapid release cycles now and that's not a bad thing. Things that don't evolve die - at least this is the perception. And developers today have a different mindset compared to 10-20 years ago.
Just have to chime in here. As someone who works with the Facebook API on a nearly daily basis, it has come a LONG way in the past year or so. When I first started with it 3-4 years ago it was an absolute nightmare. It is actually quite consistent now and they are doing a much better job of documenting / addressing bugs.
