SPL development interest

Hi Internals, SPL is an extension that is always available in PHP. It provides some classes, interfaces and functions etc. such as - ArrayObject class - Countable interface - iterator_count function What I'd like to wrap my head around is the position of this extension in PHP and the sentiments towards SPL from the Internals developers. - What is the status of this extension currently? Is it being actively developed or just supported? - Is there any interest in adding stuff here - f.ex. new classes, interfaces or traits? - And technically, how is something like ArrayObject class implemented? And should you implement it again, would it be done the same way? Thanks for your time, Jakob