(PECL ds >= 1.0.0)
Ds\Vector::map — Returns the result of applying a callback to each value
    Returns the result of applying a callback function to
    each value in the vector.
  
callback
A callable to apply to each value in the vector.
The callable should return what the new value will be in the new vector.
    The result of applying a callback to each value in
    the vector.
  
Note:
The values of the current instance won't be affected.
Exemple #1 Ds\Vector::map() example
<?php
$vector = new \Ds\Vector([1, 2, 3]);
print_r($vector->map(function($value) { return $value * 2; }));
print_r($vector);
?>
Résultat de l'exemple ci-dessus est similaire à :
Ds\Vector Object
(
    [0] => 2
    [1] => 4
    [2] => 6
)
Ds\Vector Object
(
    [0] => 1
    [1] => 2
    [2] => 3
)