SCHEME CODE FOR DATA STRUCTURES
                                       
   This section contains Scheme code to implement and manipulate many
   types of data structures in Scheme.
     * Algorithms from course 81120 "Data Structures and Algorithms"
       taught at Tampere University of Technology, Finland. These were
       written by Juha Heinanen and Pertti Kellom{ki
       (algorithms.tar.gz).
     * Alan Bawden's implementation of arrays (of dimension > 1) in
       Scheme (arrays.scm).
     * Stephen J. Bevan's functional AVL tree package (avl-tree.tar.gz).
     * Stephen J. Bevan's "trie" package, based on AVL trees
       avl-trie.tar.gz).
     * Stephen J. Bevan's implementation of character sets in Scheme
       (char-set.tar.gz).
     * Ken Dickey's implementation of simple pararmeterized hash tables
       (general-table.oo) using ../oop/yasos.tar.gz.
     * Ken Dickey's implementation of simple pararmeterized hash tables
       (general-table.scm) using standard Scheme.
     * A simple N-dimensional array package, by Lance Norskog
       (grid.scm).
     * Another N-dimensional array (matrix) package, by Todd R.
       Eigenschink (matrix-0.5.tar.gz).
     * David Carlton's implementation of a proposed record system for
       Scheme (record.tar.gz).
     * John D. Ramsdell's implementation of sets using bounded balanced
       binary trees (sets.scm).
     * Sorting functions in Scheme, by Richard A. O'Keefe (sort.scm).
     * Code to display trees on character devices, by Marc Feeley
       (tree.scm).
     * Stephen Adams' implementation of discrete sets based on balanced
       binary trees (wttree.scm and wttree.txt).