While that may seem like a silly question, if Java and Ruby both lost the data structure entirely, my code would still function. (The frameworks it runs on, not so much.)<p>It is sort of like a programmer not knowing what a NAND gate is. You could get all crotchety about that, because he couldn't do a single thing without a NAND gate on his current system... but he really doesn't need to know the specifics. Many types of programming (not all, obviously) have abstracted away memory management and have pitiful speed requirements compared to the capacity of hardware (and the bottlenecks don't happen anywhere near application code), and accordingly aside from syntactic inertia there is really not that much of a reason to care about arrays any more than there is to know about your NAND gates.<p>(Edit: It occurs to me that I could monkeypatch Array in Ruby and replace it with an associative array and my site would probably function fine... Maybe I'll try it just to prove a point.)