filterWithKey
Note
This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.
Returns a Set containing the values of the current Set that meet
a supplied condition applied to its "keys" and values
public function filterWithKey(
(function(arraykey, Tv): bool) $callback,
): Set<Tv>;
Since Sets don't have keys, the callback uses the values as the keys
as well.
Only values that meet a certain criteria are affected by a call to
filterWithKey(), while all values are affected by a call to
mapWithKey().
Parameters
(function(arraykey, Tv): bool) $callback