Functional arrays

Functional arrays are persistent: after an element is updated both the new and the old contents of the array are available for use.
Fundamental operation:
Arrays are just mappings from integer to value; any persistent map can be used as a functional array.
A fast functional array will have O(1) access and update for the common cases.
- Variant of shallow binding due to [Chuang '94]

Functional arrays are persistent: after an element is updated both the new and the old contents of the array are available for use.