PHP7 function/method signature overloading

overload.php

<?php
declare(strict_types=1);

function overload(callable ...$implementations): callable
{
    return function (...$args) use ($implementations) {
        $error = new \LogicException('Invalid overloaded implementations');
        foreach ($implementations as $candidate) {
            try {
                return $candidate(...$args);
            } catch (\TypeError $e) {
                $error = $e;
            }
        }
        throw $error;
    };
}

Usage example:

<?php
declare(strict_types=1);

class Calculator
{
    public function add(...$args)
    {
        return overload(
            function (int $num1, int $num2): int {
                return $num1 + $num2;
            },
            function (\GMP $num1, \GMP $num2): \GMP {
                return gmp_add($num1, $num2);
            }
        )(...$args);
    }
}


$calc = new Calculator();
$one = gmp_init(1);
$two = gmp_init(2);

print_r($calc->add(1, 2));        // 3
print_r($calc->add($one, $two));  // GMP Object([num] => 3)
print_r($calc->add(1.25, 2));     // TypeError: Argument 1 passed to Calculator::{closure}() must be an instance of GMP, float given

Note: declare longer signatures before ones with subset of arguments of matching types.

Released the overloading implementation as a Composer package:
https://github.com/upscalesoftware/stdlib-overloading