Hash tables and red/black trees.
Author: Frank Pfenning

Red/black trees is based on an early version of code by Chris Okasaki.
This should be updated some time (see version 15-212, Fall 1997 and
Chris Okasaki's JFP paper on red/black trees).

Updated the hash-table implementation to fix a bug in HashTable.app,
Dec 23 1997. -fp