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    Ds\Vector::reduce

    (PECL ds >= 1.0.0)

    Ds\Vector::reduce — Reduces the vector to a single value using a callback function

    Description

    public Ds\Vector::reduce(callable $callback, mixed $initial = ?): mixed

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

    Parameters

    callback
    callback(mixed $carry, mixed $value): mixed
    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.

    Return Values

    The return value of the final callback.

    Examples

    Example #1 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
    ?>

    The above example will output something similar to:

    int(30)

    Example #2 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
    ?>

    The above example will output something similar to:

    int(21)
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