This package contains an implementation of persistent immutable arrays.

("Persistent" seems to have acquired a new meaning. It no longer refers to values that outlive the execution of the program that created them, but now refers to data structures where modification actions leave the existing value unchanged.)

This implementation is extracted from the PCollections library at https://github.com/hrldcpr/pcollections. This is open-source software made available under the MIT license. The only changes are subsetting (to extract the functionality actually required) and minor formatting changes.

The code in this package is a snapshot taken on 31 October 2017.