Log Message:
Import hs-hashmap-1.2.0.1 as wip/hs-hashmap.

An implementation of persistent Map and Set containers based on
hashing. The implementation is build on top of Data.IntMap.IntMap and
Data.IntSet.IntSet, with very similar API. It uses Hashable class from
the hashable package for hashing.

This package can be used as a drop-in replacement for Data.Map and
Data.Set modules.

The Map key value is an Data.IntMap.IntMap indexed by the hash value,
containing either one (key, value) or a Data.Map.Map key value for all
keys with the same hash value.

The Set elem is an Data.IntMap.IntMap indexed by the hash value,
containing either one elem or Data.Set.Set elem for all elements with
the same hash value.