I'm running HHVM 3.2.0 and trying to get access to GET and POST request parameters. The problem is, HHVM doesn't support access to PHP superglobals ($_GET, $_POST, $_SERVER, etc).
The only other way I know of getting access to request parameters in PHP is via the filter_input function, but is that really best practice (if I'm just using the raw filter)? It seems as though HHVM should support something cleaner than that. (What about Hack?)
HHVM absolutely supports superglobals in PHP code -- they're a really key part of PHP! The docs page you've linked to is simply wrong, and I've filed a bug to get it fixed.
In strict mode Hack code, superglobals are not supported; this cookbook example shows how you can access them via partial mode.