Recursive Closure

<?php

$factorial = function (int $n) use (&factorial) {
    if ($n === 1) {
        return 1;
    }
    
    return $factorial($n - 1) * $n;
};

print factorial( 5 );

?>

To make a recursive closure, the closure must be both stored in a variable and passed as a use parameter to the same factorial.

It also works for arrow functions, although there is no the use, but the variable must be defined first, so it can be used in context later.

See Also

• Closure (PHP manual)
• All the recursive Functions in PHP
• recursive closure [Try me]

PHP Features

• closure
• arrow-function
• recursion

Last updated: 10 September 2026