Tictactoe.hs

Tictactoe.hs

data Coord = One | Two | Three deriving (Enum, Eq)
data Symb  = O | X | Nada deriving (Show, Eq)
type TicTacToe = Coord -> Coord -> Symb

showBoard :: TicTacToe -> String
showBoard b = unlines $ map showLine [One .. Three]
  where
    showLine  c    = unwords $ map (showHouse $ b c) [One .. Three]
    showHouse b' c = show $ b' c

composeBoard :: TicTacToe -> TicTacToe -> TicTacToe
composeBoard b1 b2 = b
  where b c1 c2 | b1 c1 c2 == Nada = b2 c1 c2
                | b2 c1 c2 == Nada = b1 c1 c2
                | otherwise        = b1 c1 c2

play :: TicTacToe -> Coord -> Coord -> Symb -> TicTacToe                
play b c1 c2 player | b c1 c2 == Nada = composeBoard b b'
                    | otherwise       = b
  where b' c1' c2' = if   c1'==c1 && c2'==c2 
                     then player 
                     else Nada

emptyBoard :: TicTacToe
emptyBoard = (const . const) Nada

main = do
  let
    b1 = play emptyBoard Two Two O
    b2 = play b1 One One X
    b3 = play b2 One One O
    b4 = play b3 Three One X
  putStr $ showBoard b4