It looks promising, I highly dislike writing PHP and this seems like it might ease the pain, but they could've gotten rid of the damn dollar sign in front of variables, how ugly is this? "return ($y) ==> { return $y + 1; }"
Edit: My previous comment was referring to the second occurrence of "return" in your example (after the "==>" arrow). Just noticed I mistakenly dropped the first occurrence of "return"; the first occurrence of "return" in your example is needed.
You can actually write you example a bit more concisely in Hack: "$y ==> $y + 1".