Closures cannot be serialized. Superclosure can.

Code
<?php

use SuperClosure\SerializableClosure;

$hello = function($world) {
    echo 
'Hello ' $world;
};

// A Closure cannot be serialized
try {
    
serialize($hello);
}
catch(
Exception $e) {
    echo 
$e->getMessage() . PHP_EOL PHP_EOL;
}

$closurer = new SerializableClosure($hello);

$serialized serialize($closurer);
$unserialized unserialize($serialized);

$unserialized('world');
Result
Serialization of 'Closure' is not allowed

Hello world