Ds\Sequence::reduce

    (PECL ds >= 1.0.0)

    Ds\Sequence::reduce — Reduces the sequence to a single value using a callback function

    Опис

    abstract public function Ds\Sequence::reduce(callable $callback, mixed $initial = ?): mixed

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

    Параметри

    callback
    function 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.

    Значення, що повертаються

    The return value of the final callback.

    Приклади

    Приклад #1 Ds\Sequence::reduce() with initial value example

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

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

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

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

    Поданий вище приклад виведе щось схоже на:

    int(30)

    Приклад #2 Ds\Sequence::reduce() without an initial value example

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

var_dump($sequence->reduce(function($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
?>

    Поданий вище приклад виведе щось схоже на:

    int(21)

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