Sounds like they added optional type declarations, lambda expressions, and a few more goodies to PHP. I am reminded of http://en.wikipedia.org/wiki/Greenspun%2

Sounds like they added optional type declarations, lambda expressions, and a few more goodies to PHP. I am reminded of http://en.wikipedia.org/wiki/Greenspun%27s_tenth_rule http://en.wikipedia.org/wiki/Greenspun%27s_tenth_rule. Facebook is now at sufficient scale where they are reimplementing Common Lisp on top of PHP.