HH\Set::mapWithKey

Returns a Set containing the values after an operation has been applied to each "key" and value in the current Set

public function mapWithKey<Tu as arraykey>(
  (function(arraykey, Tv): Tu) $callback,
): Set<Tu>;

Since Sets don't have keys, the callback uses the values as the keys as well.

Every value in the current Set is affected by a call to mapWithKey(), unlike filterWithKey() where only values that meet a certain criteria are affected.

Parameters

• (function(arraykey, Tv): Tu) $callback

Returns

• Set<Tu> - a Set containing the values after a user-specified operation on the current Set's values is applied.