Reversi Board

The first issue in dealing with “true reversi” is getting pieces from the board.

Board Access

We will write a function to get the piece at a given location on the board. This would be simple, except what should we do when that location is empty?

Unoccupied

We will make a special piece that we use to indicate that the location is empty. You should make your own by filling in ZZZ with an appropriate string or number.

(define UNOCCUPIED (make-piece ZZZ (make-posn XXX YYY))

An in-person discussion about how to fill in XXX and YYY would make sense. Otherwise just pick some huge numbers that are definitely not on the board.

After those choices, we are ready to write a function that tells if a posn (location) is occupied.

unoccupied-piece?: piece -> boolean
occupied?: list-of-pieces(board) posn(loc) -> boolean

Get Pieces

The get-piece function returns the Piece at a given location on the board, or UNOCCUPIED if the location is empty.

get-piece: list-of-pieces(board) posn(loc) -> piece

Notice the signature! Don’t get confused and return “unoccupied” (a string) instead of the UNOCCUPIED Piece defined above.