Visual Representation of Knowledge
When describing a microworld, we would like to be able to add visual semantics (graphics) for the knowledge, bringing the microworld to life.
In fact, in Etoys the graphical model is the very first thing we implement when creating an object.
For example, the semantic of action "drop" is merely changing of an object's location from one name to another. However, the visual extension of knowledge may also attribute it to a nice graphical semantics, maybe a nice animation of the object dropping with the right acceleration from its origin to target.
The JOHN language supports visual description of classes via the visual command, which tells the machine how to graphically represent the object.
Currently ASCII art is the default graphics for printing objects, which is done via the draw command.