PHP Memoization inspired by @CViniciusSDias

memoization.php

<?php

use Ds\Map;

function memo(callable $function): callable
{
    $cache = new Map();
    return function (mixed ...$args) use (&$cache, $function): mixed {
        if (isset($cache[$args])) {
            return $cache[$args];
        }

        $result = $function(...$args);
        return $cache[$args] = $result;
    };
}

function sum(int $a, int $b): int
{
    echo 'Executing sum.'.PHP_EOL;
    return $a + $b;
}

$sum = memo(fn(...$args) => sum(...$args));

echo $sum(1, 2).PHP_EOL;
echo $sum(1, 3).PHP_EOL;
echo $sum(1, 2).PHP_EOL; // Should use cache
echo $sum(1, 3).PHP_EOL; // Should use cache