Memoize default hashFunction can't recognize different Closures

[radmen]

Simple example first:

<?php
$foo = function($no) {
  return "Foo: {$no}\n";
};

$bar = function($no) {
  return "Bar: {$no}\n";
};

$foo_mem = __::memoize($foo);
$bar_mem = __::memoize($bar);

echo $foo_mem(5);
echo $bar_mem(5);

The output of this script is:

$ php test.php
Foo: 5
Foo: 5

It's because var_export can't properly export Closure's. It's better to use spl_object_hash() in hash function.
I have simple (and yet stupid) example of hash function:

<?php
$hash = function($function, $args) {
  return md5(join('_', array(
    spl_object_hash($function),
    var_export($args, true),
  )));
};

$foo = function($no) {
  return "Foo: {$no}\n";
};

$bar = function($no) {
  return "Bar: {$no}\n";
};

$foo_mem = __::memoize($foo, $hash);
$bar_mem = __::memoize($bar, $hash);

echo $foo_mem(5);
echo $bar_mem(5);

Maybe it's time to implement better default hash function? What do You think about it?
In free time, I'll try to propose my implementation of it.

[radmen]

Ah, forgot to write. The issue is on PHP 5.3.8