I think part of it comes down to mindset. If you think of ArrayList as an abstract container, then yes, you're totally correct that having the underlying data s

I think part of it comes down to mindset. If you think of ArrayList as an abstract container, then yes, you're totally correct that having the underlying data structure being exposed is a bit jarring and unexpected. But I don't think that's the right level of abstraction to come from. ArrayList is just a wrapper around a slice that handles allocation and deallocation for you: the underlying data structure is part of the contract of the type, allowing it to be almost a drop in replacement.