I haven't tested it. Don't expect it to work.
var_dump(callable_equals(
['Foo', 'bar'],
'foo::BAR'
));
var_dump(callable_equals(
['A\\b\\C\\d\\Foo', 'bAr'],
'a\\B\\c\\D\\FoO::bar',
['A\\b\\c\\d\\foo', 'BAR']
));
var_dump(callable_equals(
[new ArrayObject, 'append'],
[new ArrayObject, 'append']
));
var_dump(callable_equals(
[new ArrayObject, 'append'],
[new ArrayObject, 'append'],
false
));