I made phc (http://phpcompiler.org http://phpcompiler.org), which is conceptually similar to HippyVM, before applying to YC. And I got into YC, and now run a po

I made phc (http://phpcompiler.org http://phpcompiler.org), which is conceptually similar to HippyVM, before applying to YC. And I got into YC, and now run a post-Series A startup, so I probably have a tiny bit of insight. Trying to sell a PHP compiler is a very bad business plan. In fact, trying to sell any compiler is a very bad business plan, because you're basically competing with free. You have to compete against OSS with massive communities (like gcc) or against deep pockets (like Visual Studio) or against reference implementations (like the OSS PHP engine). Imagine trying to sell a PHP compiler. You can try to get wide community adoption and sell bottom-up. Good luck with that, the PHP community is not that interested in tools. So you can try to sell top-down to enterprises with slow PHP problems. Very few companies have slow PHP problems, and those that do could just use HHVM. For 30 years, commercial lisp engines, C++ compilers, Java VMs, and tons of similar things have all been commercially unsuccessful (though not all failed outright). A PHP engine will have to compete with with Facebook's HHVM (OSS + deep pockets), against the Zend engine (community adoption + reference implementation) and against Zend corp (a known and established quantity in the space). I spent a bit of time in compiler research and met with tons of compiler companies at events. One of them said that they couldn't think of any compiler company that didnt make its money off consulting, and that worse, about 85% of them made their money off a single client. Quick, name a successful compiler company! There aren't too many and they weren't that famous. There is Coverity in the closely related static analysis space, that sold for $375m. There is Cilk that sold to intel for $100m. Dredging my memory there's companies like Anamorphic which was acquihired by Sun in 97 to work on Java. You're almost better off being a HHVM consultancy than building a competing compiler and ending up having to innovate on the product as well as providing consulting.