 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2019/functional-programming-design-and-analysis-of-algorithms/3/b/solution

The empty occupancy sets leave all nine coordinates available:

empty :: Board
empty = ([],[],[(r,c) | r <- [0..2], c <- [0..2]])

This board satisfies the representation invariant and gives O the next move.

 New to topics? Read the docs here!