Online PHP editor | refs for g9bR2

<?php // This code works with PHP 7.4. // Older versions of PHP are counter-revolutionary. namespace stalin; function sort(array $xs): array { if (count($xs) <= 1) { return $xs; } $zs = $xs; $x = array_shift($zs); $y = array_shift($zs); if ($x <= $y) { return [$x, ...sort([$y, ...$zs])]; } return sort([$x, ...$zs]); } echo json_encode(sort([1, 2, 1, 1, 4, 3, 9]));