Object deck:

10 dict begin
  /Integer 123 def
  /String (abcdefghijklmnopqrstuvwxyz0123456789) def
  /Name /don def
  /Array [1 2 3 4 5] def
  /Dictionary 10 dict def
  Dictionary begin
    /one 1 def
    /two 2 def
    /three 3 def
    /four 4 def
  end
currentdict end

Push the integer, string, and name onto the stack.
Show each of them visually.
zap them

Push the array onto the stack.
Open it up. 
Push the numbers on the stack, add them, paste them back.
Arrays are polymorphic: paste name, string into array.

Push the dictionary onto the stack.
Open it up.
Push numbers, paste in strings, name, array.

Arrays can hold dictionaries, dictionaries can hold arrays.
Arrays and dictionaries can even hold references to themselves.

Type in an array of numbers, [1 2 3 4 5 6]
Show it. 
Paste one long string into it at 5.
Paste it into itsself at 1.
Redisplay it.
Increase depth.
Redisplay it.
Move self reference to 2.
Redisplay it.
Make another self reference.
Redisplay it.

User interface objects are built out of PostScript 
data structures in NeWS.
Object oriented programming package uses dictionaries 
to represent classes and instances.
Root menu instance dictionary
  show real root menu
  display it.
  deepen it. redisplay it, while popping up submenus

Representing other structures as PostScript data

File directory
  hierarchy
  dictionary represents directory
  array represents file

Arpanet map
  Long haul packet switching computer network (as of 1985)
  Each dictionary represents one "Packet Switching Node" on the network, 
  and contains links to the node's neighbors.

Distinctive looking array of strings.

Editing data structures:

Grab a few arpanet nodes, indicate where they are on the map,
and paste some data structures into them.
Travel around the net hunting for them.