This is very interesting to me but not really revolutionary since I am so used to languages like javascript where array indices don't matter the same way they do in C. However, I do see the utility in being able to generate new "views" of an existing array by offsetting all indices by a set amount.
First thing that comes to mind is time-series data - like a sliding window based on some concept of "now" where indices can be offset by the current date/time. (e.g. timeSeries[0] == now, timeSeries[-1] == one second ago, timeSeries[1] == one second in the future, etc.)
I actually find these linear-algebra based languages even more mind-bending than functional based languages.
If you do this in JavaScript, you won't be able to use many standard array operations or get standard array performance. The specification explicitly only supports non nonnegative indices for real arrays.
You're just using Object/map behavior, and if you're doing that with negative indices on an Array Object you're misusing it.
First thing that comes to mind is time-series data - like a sliding window based on some concept of "now" where indices can be offset by the current date/time. (e.g. timeSeries[0] == now, timeSeries[-1] == one second ago, timeSeries[1] == one second in the future, etc.)
I actually find these linear-algebra based languages even more mind-bending than functional based languages.