PHP's array_zip

array_zip.php

<?php

declare(strict_types=1);

function array_zip(array ...$arrays): array
{
    // Applied suggestion from reddit
    // https://www.reddit.com/r/PHP/comments/76czco/php_equivalent_of_pythons_zip_function/doe5j86/
    return \array_map(null, ...$arrays);
}

// Example usages:
//
// $tuples_array = array_zip([1,2,3]);
// $tuples_array === [ [1], [2], [3] ]
//
// $tuples_array = array_zip([1,2,3], [4,5,6]);
// $tuples_array === [ [1,4], [2,5], [3,6] ]
//
// $tuples_array = array_zip([1,2,3], [4,5]);
// $tuples_array === [ [1,4], [2,5], [3,null] ]
//
// $tuples_array = array_zip([1,2,3], [4,5,6], [7, 8, 9]);
// $tuples_array === [ [1,4,7], [2,5,8], [3,6,9] ]

////////////////////////////////////////////////////////////////////////////////
// Here you have a more useful construct, the same for iterators:             //
// the aim is to use less memory in some cases                                //
////////////////////////////////////////////////////////////////////////////////

function iterable_zip(iterable ...$iterable_list): \Generator
{
    /** @var \Iterator[] $_iterable_list */
    $iterators = \array_map('iterable_to_iterator', $iterable_list);

    while (contains_valid_iterator($iterators)) {
        // WARNING: Be aware that this array_map call has side effects (on the iterator)!
        yield \array_map(
            function (\Iterator $iterator) {
                if ($iterator->valid()) {
                    $v = $iterator->current();
                    $iterator->next();
                    return $v;
                } else {
                    return null;
                }
            },
            $iterators
        );
    }
}

function iterable_to_iterator(iterable $stream): \Iterator {
    if ($stream instanceof \Iterator) {
        return $stream;
    } elseif ($stream instanceof \IteratorAggregate) {
        return iterable_to_iterator($stream->getIterator());
    } elseif (\is_array($stream)) {
        return new \ArrayIterator($stream);
    } else {
        throw new \RuntimeException('Impossible state');
    }
}

/**
 * @param \Iterator[] $iterators
 * @return bool
 */
function contains_valid_iterator(array $iterators): bool
{
    return \array_reduce(
        $iterators,
        function (bool $carry, \Iterator $stream) {
            return $carry || $stream->valid();
        },
        false
    );
}