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 $y + 1; }"
You can actually write you example a bit more concisely in Hack: "$y ==> $y + 1".
If the right hand side _is_ wrapped in curly braces then it is treated as a list of statements, in which case you do need to use the "return" keyword.