On the PHP Addiction blog today, there's a new post where Doug Hill asks a question of his fellow developers - are there advantages to having a standard container library for PHP?
Most compiled languages that I have used have some kind of container implementation, Lists, Maps, Trees, Stacks and all their many variations. PHP has arrays and the SPL.
The only problem he's noted so far is that containers made in userland would be slower than ones created natively. A comment from Antony Dovgal points out a project similar to what he's looking for that's already in the works.