It wouldn't be that hard if you did it in userland (i.e. pure PHP). But you also need to switch around inconsistent parameter orders (e.g. haystack vs needle) a

It wouldn't be that hard if you did it in userland (i.e. pure PHP). But you also need to switch around inconsistent parameter orders (e.g. haystack vs needle) and disable the use of the old ones (which can't really be done w/ the pure PHP aliases). The docs are just docbook, but have had a ton of work, you'd be best to PHPDoc your new methods. The problem is speed and compatibility. If you did it natively you'd have to do it twice, once for HHVM and once for the Zend engine. If you did it in pure PHP it would cause performance issues since the interpreter isn't smart enough to inline (maybe HHVM is, but even it will take a trace or two to realize the JIT need probably).