(PECL ds >= 1.0.0)
Ds\Map::apply — Updates all values by applying a callback function to each value
    Updates all values by applying a callback function to
    each value in the map.
  
callback
A callable to apply to each value in the map.
The callback should return what the value should be replaced by.
Не повертає значень.
Приклад #1 Ds\Map::apply() example
<?php
$map = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);
$map->apply(function($key, $value) { return $value * 2; });
print_r($map);
?>Поданий вище приклад виведе щось схоже на:
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 2
        )
    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 4
        )
    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 6
        )
)
