Checkers Model

This is the written record of an analysis. You should practice doing your own analysis of a game, not just copying this one.

Examples

Begin with pictures of all of the situations that can come up in the game.

Advanced: enthusiastic software designers may want to read about how user stories used in actual software development.

Board Coordinates

We considered human-friendly coordinates, like (1,4) as well as computer-friendly coordinates like (75, 225). Using computer coordinates would make it easier to write the draw-handler, but writing checks would be easier with human coordinates. We chose human coordinates because checks are important to write.

In this writeup, our board coordinates go from 0 through 7 in each direction.

Piece Structure

• p: Posn
• c: Player (Integer)
• king?: Boolean

Model Structure

The model keeps track of whose turn it is, where the pieces are, and which piece (if any) is currently selected and ready to move.

• turn: Player (Integer)
• ps: (Listof Piece)
• selected: Piece

When there is no piece selected, we will put a special piece in the selected location that could not arise in the game: say a king for player 3 located at (-1000,1000).

The fancier way of representing the selected piece is to use the type (Option Piece), but that doesn’t simplify the rest of the work.