I like the idea! I would model it after JavaScripts Object.fromEntries() and Object.entries() function and have both functions available.

@lstrojny I'm not too versed in JavaScript, but from MDN:

Return:
An array of the given object's own enumerable string-keyed property [key, value] pairs

Object.entries can already be achieved by casting an array to an (object) (and the converse with a cast to (array)):

php > $obj = (object) ['a' => 3];
php > var_dump($obj);
object(stdClass)#1 (1) {
  ["a"]=>
  int(3)
}
php > var_dump($obj->a);
int(3)
php > var_dump((array) $obj);
array(1) {
  ["a"]=>
  int(3)
}

So I don't see the connection. I want to return an integer-keyed array, specifically
These may also be useful, for sure, but unless I'm not understanding it right, it'd be a completely different pair of functions

Just to clarify: Object.entries() does exactly what your (and Python's) enumerate() does and Object.fromEntries() does the opposite.

So this is how it could look for Functional:

Functional\entries(['foo' => 'bar', 'baz' => 'bla']); // [['foo', 'bar'], ['baz', 'bla']]
Functional\from_entries([['foo', 'bar'], ['baz', 'bla']]); // ['foo' => 'bar', 'baz' => 'bla']

Ah, I see! Yes, that would be useful, but there's a subtle difference in the way I made it:

Functional\enumerate(['H' => `'Hydrogen']);` // [0 => ['H' => 'Hydrogen]]

Difference being that it keeps the key-value map, meaning it can be reversed with array_merge(...$enumerated).

I'm not entirely sure which is more useful in general. The one I implemented was the one I wanted, but I'll defer to you as to which you prefer/think is more useful

Not sure if this destructuring syntax is legal in PHP, though.

foreach (enumerate($this->hash) as $i => [$k => $v]) {
    // ...
}

But with @lstrojny suggestion you could do:

foreach (entries($this->hash) as $i => [$k, $v]) {
    // ...
}

@lstrojny I updated the code as per your recommendations

The failing tests seem to be unrelated to my changes (I hope)

I've made the changes you requested, I believe. Apologies for the delay

I believe it's finally done :)

Great, thank you for your patience!

@lstrojny Has this been released?