I would indeed prefer
:= rather than
= for mutable assignment. But at least that's a deliberate trade somebody made for a reason (there is no good single ASCII character for this).
Whereas there is no real rationale for "vector" meaning dynamic array other than people got used to it in C++ (and now Rust), so it's a bit unfortunate because it was a chance to start fresh and drop that bit of legacy C++ baggage.
I understand that Arr wouldn't convey the dynamic aspect, but not sure if that's really a deal breaker. After all, "str" and "String" have some different properties too and are both called strings. And sure, pronunciation sounds pirate, but pronouncing Rc is even harder.
But there are plenty of other options,
Arr was really an example proposal. I didn't really expect this to go through. If people actually wanted to change it, I'm sure there'd be a long discussion and somebody would have come up with a better proposal.
Da<T> (for dynamic array)?
List<T>? Plenty of reasonable names.