PHP has quite a lot of oddities such as how loose comparisons (`==`) are made, numeric-strings, and type coercion. But the two oddities mentioned in the article are not that "odd" with a bit of context.

- PHP has `SplFixedArray`[^1] that work similar to the standard arrays you expect from other languages. SPL extension is always available in PHP 5.3+, it is not even possible to compile PHP without it anymore. There is no specific type for list-arrays and associative arrays, but there is an `array_is_list` function to quickly check it.

- For typed properties, if a property is not typed, it is effectively considered `mixed $var = null`. If the property is typed, and has no default value, then it is considered uninitialized, and not allowed to access.

[^1]: https://www.php.net/manual/en/class.splfixedarray.php