HH\ImmMap::filterWithKey

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

public function filterWithKey(
  (function(Tk, Tv): bool) $callback,
): ImmMap<Tk, Tv>;

Only keys and values that meet a certain criteria are affected by a call to filterWithKey(), while all values are affected by a call to mapWithKey().

The keys associated with the current ImmMap remain unchanged in the returned ImmMap; the keys will be used in the filtering process only.

Parameters

• (function(Tk, Tv): bool) $callback

Returns

• ImmMap<Tk,Tv> - an ImmMap containing the values after a user-specified condition is applied to the keys and values of the current ImmMap.

Examples

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