With how good PHPDoc and Phan are these days I don't really think about it anymore. You can sort of have typed array by implementing Iterator, Countable, ArrayAccess, and optionally Indexing but I assume you mean defining types of array values.
declare(strict_types=1);
/\* @var array<string, int> \*/
function foo(string $key) {
echo $key;
}
$foo = [
'a' => 10,
'1' => 15,
];
foreach ($foo as $key => $_) {
foo($key);
}
PHP arrays are the most versatile part of the language. They're what actually makes the language so good in so many ways.
But typed arrays are a freaking requirement at this point and I've been screaming about it for years now... alas no response.
I wish that the implicit casting you describe only happened in the two first case. In your example PHP already knows that $foo is a hashmap, so I'd want it to keep '1' as is!
Unfortunately for all of us, for every person surprised by this behavior, there's someone who relies on it. So it'll never change.
Best we can hope is to have better array types eventually (no, the SPL isn't it).