Hello, I think your type should be: type Board a b c d e f g h i = Either (Three a b c) (Either (Three d e f) (Either (Three g h i) (Either (Three a d g) (Either (Three b e h) (Either (Three c f i) (Either (Three a e i) (Three c e g))))))) as far as i can understand, it seems thats it's mandatory for Player 1 to play in a,b,c to win? So victory should go to player 2? Cheers, Corentin On 4/16/10, Dan Piponi wrote:

On Thu, Apr 15, 2010 at 4:58 PM, Ashley Yakeley wrote:

...

type Board a b c d e f g h i = Either (Three a b c) (Either (Three d e f) (Either (Three g h i) (Either (Three a d g) (Either (Three b e h) (Either (Three c f i) (Either (Three a e i) (Either (Three c e g) )))))))

In the service of readability we could also define:

data X = X data O

Though the victory conditions aren't precisely the usual ones. -- Dan _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe