ConstSet::filterWithKey

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

public function filterWithKey(
  (function(arraykey, Tv): bool) $fn,
): ConstSet<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) $fn - The callback containing the condition to apply to the current ConstSet "keys" and values.

Returns

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