Add play and main function to game of nim

Author: evturn

10-interactive-programming/10.8-nim.hs

@@ -34,10 +34,38 @@ putBoard [a,b,c,d,e] = do putRow 1 a
 
 getDigit :: String -> IO Int
 getDigit prompt = do putStr prompt
-                      x <- getChar
-                      newline
-                      if isDigit x the
-                         return (digitToInt x)
-                      else
-                         do putStrLn "ERROR: Invalid digit"
-                            getDigit prompt
+                     x <- getChar
+                     newline
+                     if isDigit x then
+                        return (digitToInt x)
+                     else
+                        do putStrLn "ERROR: Invalid digit"
+                           getDigit prompt
+
+newline :: IO ()
+newline = putChar '\n'
+
+play :: Board -> Int -> IO ()
+play board player = 
+   do newline
+      putBoard board
+      if finished board then
+         do newline
+            putStr "Player "
+            putStr (show (next player))
+            putStrLn " wins!"
+      else
+         do newline
+            putStr "Player "
+            putStrLn (show player)
+            row <- getDigit "Enter a row number: "
+            num <- getDigit "Stars to remove: "
+            if valid board row num then
+               play (move board row num) (next player)
+            else
+               do newline
+                  putStrLn "ERROR: Invalid move"
+                  play board player
+
+nim :: IO ()
+nim = play initial 1