Hack Transpiler
Today, we’re proud to announce a first, experimental release of
h2tp, or the “HH (Hack) Transpiler,” a tool which allows projects that have converted from PHP to Hack to still make releases that target the PHP language.[…]
But transforming Hack code using collections is not merely about using equivalent constructs from the hacklib library. For example, on HHVM, empty Hack collections universally convert to
falsewhen used in a boolean context, something a standard PHP object can never do. This means that any arbitrary expression or statement that involves a boolean comparison, or any cast, might invoke this special rule if it involves a collection. So unless the expression being treated as boolean is trivially not a collection, we have to treat it as if it might potentially contain a collection. Hence, we have to be very cautious when making transformations.[…]
In a few rare cases we actually have to choose not to support a feature. For instance, we do not support Instance variables using literal syntax in the class declaration.
