## Extending Richard Bird's Sudoku Solver

Due *Tuesday, May 15, at 11:59PM*
If you want to learn a little Haskell, for extra credit you can extend
Richard Bird's Sudoku solver to handle Sudoku+, which is like Sudoku
except there is an additional requirement: the diagonals must contain
distinct digits.

You're free to turn in a solution any time before reading period ends.