Hack also introduces a few new operators beyond those which exists in PHP.
==> (Lambda operator)
Allows for a more concise representation of PHP closures with the benefit of capturing variables from the enclosing function body implicitly.
?-> (null-safe operator)
Allows for method and property calls without explicit checks to ensure that the object being referenced is non-
Allows for accessing XHP attributes without explicitly having to call
getAttribute() on the XHP object.
|> (Pipe operator)
Allows for a fluid, concise syntax for chaining expressions.