Correct -- they handle the idiom more gracefully in the context of an array-backed list, not an array. I elided the two as postgres arrays don't quite fit clean

Correct -- they handle the idiom more gracefully in the context of an array-backed list, not an array. I elided the two as postgres arrays don't quite fit cleanly into either. (For example, evaluating arr[i] is O(i) for postgres arrays of variable width types.)