added comments in cli

TTTCLI.hs

@@ -1,4 +1,5 @@
 import TicTacToe
+import System.Exit
 
 main = tictactoe $ Right initialBoard
 
@@ -7,22 +8,29 @@ tictactoe bmsg = case bmsg of
                       (Left msg) -> putStrLn msg
                       (Right b) -> nextRound b
 
-
 nextRound :: Board -> IO ()
 nextRound b = do
+
+  -- check if one of the players won the game
   case checkWinnerPure b of
     Nothing -> putStrLn $ "Player's turn: " ++ (show $ currentPlayer b)
     Just p -> do
       putStrLn $ "Player " ++ show p ++ " won the game"
-      tictactoe $ Right initialBoard 
+      exitSuccess
+
+  -- determine current player and output info
   let p = currentPlayer b
   putStrLn $ show b
+
+  -- get choice from input
   putStr "Column: "
   col <- getLine
   let colNum = read col
   putStr "Row: "
   row <- getLine
   let rowNum = read row
+
+  -- make choice on board
   case mkChoice (colNum,rowNum,p) b of
        Left msg -> do
          putStrLn msg

TicTacToe.hs

@@ -50,8 +50,6 @@ mkChoice c@(col, row, m) b
   | otherwise = Left $ "Choice " ++ show c ++ " is not allowed."
   where validChoice = isEmpty (col, row) b && isValidIndex (col, row) 
         r = newRow (col, m) (rowAtIndex row b)
-
-
 
 
 -- checks the range of the indices
@@ -99,10 +97,22 @@ newRow (col, m) (RowCons f0 f1 f2)
   | col == 1 = RowCons f0 (FieldCons m) f2
   | col == 2 = RowCons f0 f1 (FieldCons m)
 
-
-checkWinner :: BoardOrMsg -> Maybe Marker
-checkWinner (Right b)    = checkWinnerPure b
-checkWinner (Left msg) = Nothing
+checkWinner :: Board -> BoardOrMsg
+checkWinner b = 
+  let w0 = checkRows b in
+  case w0 of
+    Just m -> Left $ "Player won: " ++ show m 
+    Nothing -> let w1 = checkCols b in
+      case w1 of
+        Just m -> Left $ "Player won: " ++ show m 
+        Nothing -> let w2 = checkDiagonals b in
+          case w2 of
+            Just m -> Left $ "Player won: " ++ show m 
+            Nothing -> return b
+
+checkWinner' :: BoardOrMsg -> Maybe Marker
+checkWinner' (Right b)    = checkWinnerPure b
+checkWinner' (Left msg) = Nothing
 
 checkWinnerPure :: Board -> Maybe Marker
 checkWinnerPure b = let res0 = checkRows b in