Ds\Vector::reduce

Reduces the vector to a single value using a callback function

&reftitle.description; public `mixed` `Ds\Vector::reduce` `callable` `callback` `mixed` `initial`

Reduces the vector to a single value using a callback function.

&reftitle.parameters;

`callback`

- `mixed```callback`` `mixed` `carry` `mixed` `value`

  `carry`

- The return value of the previous callback, or `initial` if it's the first iteration.

`value`

- The value of the current iteration.

`initial`

- The initial value of the carry value. Can be &null;.

&reftitle.returnvalues;

The return value of the final callback.

&reftitle.examples;

### `Ds\Vector::reduce` with initial value example

    <?php
    $vector = new \Ds\Vector([1, 2, 3]);

    $callback = function($carry, $value) {
        return $carry * $value;
    };

    var_dump($vector->reduce($callback, 5));

    // Iterations:
    //
    // $carry = $initial = 5
    //
    // $carry = $carry * 1 =  5
    // $carry = $carry * 2 = 10
    // $carry = $carry * 3 = 30
    ?>

&example.outputs.similar;

    int(30)

### `Ds\Vector::reduce` without an initial value example

    <?php
    $vector = new \Ds\Vector([1, 2, 3]);

    var_dump($vector->reduce(function($carry, $value) {
        return $carry + $value + 5;
    }));

    // Iterations:
    //
    // $carry = $initial = null
    //
    // $carry = $carry + 1 + 5 =  6
    // $carry = $carry + 2 + 5 = 13
    // $carry = $carry + 3 + 5 = 21
    ?>

&example.outputs.similar;

    int(21)