HH\ImmSet::filterWithKey

Returns an ImmSet containing the values of the current ImmSet that meet a supplied condition applied to its "keys" and values

public function filterWithKey(
  (function(arraykey, Tv): bool) $callback,
): ImmSet<Tv>;

Since ImmSets 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

Returns

• ImmSet<Tv> - an ImmSet containing the values after a user-specified condition is applied to the values of the current ImmSet.

Examples

See [Set::filterWithKey](</hack/reference/class/Set/filterWithKey/#examples>) for usage examples.