That is exactly what the framework uses pure PHP just have a look in the API or the vendor folder.
it's straight PHP doing the shortcuts in the background for you.
Some classes that appears when you type php -m in console are not the same name you have to instantiate in code.
For example, if i see here what PHP extensions i have when type php -m , i have one that is named zip, but if i try to instantiate zip like $zip = new \Zip() it says class not found, instead, the correct way is $zip = new \ZipArchive() . So, give a try with this class (zip) and tell me what you get.