我在MancalaBoard.hs中有一个看起来像这样的函数：
allowedMoves :: MancalaBoard -> Player -> [Int]
allowedMoves board p
| (p == PlayerA && getCurPlayer board == p) = findIndices (>0) (init(take (length (playerSide board PlayerA)+1) (getBoardData board)))
| (p == PlayerB && getCurPlayer board == p) = map (+(length (playerSide board PlayerA))) (findIndices (>0) (init(drop (length (playerSide board PlayerA)) (getBoardData board))))
| otherwise = []
供参考，MancalaBoard就是这样：
data MancalaBoard = MancalaBoardImpl [Int] Player
当我运行MancalaBoard.hs时，我可以这样做：
*MancalaBoard> let board = [5,0,2,7,0,1,5,6,1,7,7,5,0,2] :: [Int]
*MancalaBoard> let mboard = MancalaBoardImpl board PlayerB
*MancalaBoard> move mboard 7
Player A: [5,0,2,7,0,1,5]
Player B: [0,2,8,8,6,1,3]
Current turn: PlayerB
但我有另一个名为TwoPlayerMancala.hs的文件导入了MancalaBoard。当我尝试在此文件中执行相同的操作时，出现错误：
Player A: [5,0,2,7,0,1,5]
Player B: [6,1,7,7,5,0,2]
Current turn: PlayerB
Player B, please make your move
7
*** Exception: Not an allowed move
知道为什么会这样吗？以下是两个文件的完整副本，以防它有用：
module MancalaBoard (MancalaBoard, Player, initial, getCurPlayer,
getBoardData, numCaptured, move, allowedMoves, isAllowedMove,
gameOver, winners) where
import Data.List as List -- for List.elemIndex
import Data.Maybe as Maybe -- for List.elemIndex
{-
- The stones on a Mancala board are simply recorded as a list of Ints. The
- Ints come in the following order:
- 1. The boardSize pits belonging to PlayerA
- 2. The store belonging to PlayerA
- 3. The boardSize pits belonging to PlayerB
- 4. The store belonging to PlayerB
-}
data MancalaBoard = MancalaBoardImpl [Int] Player
data Player = PlayerA | PlayerB deriving (Eq, Show)
---- Functions/constants for Player ----
allPlayers = [PlayerA, PlayerB]
numPlayers = length allPlayers
playerNum :: Player -> Int
playerNum p = fromJust $ List.elemIndex p allPlayers
playerWithNum :: Int -> Player
playerWithNum i = allPlayers !! i
nextPlayer :: Player -> Player
{- Find the player whose turn is next -}
nextPlayer p = playerWithNum $ ((playerNum p) + 1) `mod` numPlayers
---- Functions/constants for MancalaBoard ----
{- number of pits on each side -}
boardSize = 6
{- number of stones in each pit -}
startStones = 4
{- the initial mancala board -}
initial :: MancalaBoard
initial = MancalaBoardImpl (concat $ take numPlayers (repeat boardSide)) PlayerA
-- One side of board pit at end
where boardSide = take boardSize (repeat startStones) ++ [0]
{- return the index of the first pit belonging to a player -}
indexForFirstPit :: Player -> Int
indexForFirstPit p = (playerNum p) * (boardSize + 1)
{- return the index of the store for that player -}
indexForPlayerStore :: Player -> Int
indexForPlayerStore p = boardSize + (indexForFirstPit p)
{- return the indices for the pits (without the store) for a player -}
indicesForPlayerSide :: Player -> [Int]
indicesForPlayerSide p = [firstPit .. lastPit] where
firstPit = indexForFirstPit p
lastPit = firstPit + boardSize - 1
---- Retrieve information about Mancala Board
{- return the player who has the current turn -}
getCurPlayer :: MancalaBoard -> Player
getCurPlayer (MancalaBoardImpl xs player) = player
{- return the list of all pits in the board -}
getBoardData :: MancalaBoard -> [Int]
getBoardData (MancalaBoardImpl xs player) = xs
{- return the side of the board for a specified player, including the store at
- the end -}
playerSide :: MancalaBoard -> Player -> [Int]
playerSide (MancalaBoardImpl xs player) p
| (p == PlayerA) = take (length xs `div` 2) xs
| (p == PlayerB) = drop (length xs `div` 2) xs
{- return the number of captured pieces in specified player's store -}
numCaptured :: MancalaBoard -> Player -> Int
numCaptured board p = last $ playerSide board p
{- allowedMoves returns a list of valid moves for the current player:
- ie. the indices of pits which belong to that player, and which contain one
- or more pieces -}
allowedMoves :: MancalaBoard -> Player -> [Int]
allowedMoves board p
| (p == PlayerA && getCurPlayer board == p) = findIndices (>0) (init(take (length (playerSide board PlayerA)+1) (getBoardData board)))
| (p == PlayerB && getCurPlayer board == p) = map (+(length (playerSide board PlayerA))) (findIndices (>0) (init(drop (length (playerSide board PlayerA)) (getBoardData board))))
| otherwise = []
{- check that a move is valid for the current player -}
isAllowedMove :: MancalaBoard -> Int -> Bool
isAllowedMove board q = q `elem` allowedMoves board (getCurPlayer board)
{- We number the pits from 0 to 13 (2 players, 6 pits each and 1 store each)
- This function takes a board and applies the move where the player selects
- the numbered pit, giving back an updated board after the move -}
move :: MancalaBoard -> Int -> MancalaBoard
move (MancalaBoardImpl xs PlayerA) n
| ((isAllowedMove (MancalaBoardImpl xs PlayerA) n) == True) = (MancalaBoardImpl intmap (choose PlayerA))
| otherwise = error "Not an allowed move" where
q = xs !! n
plusoned = map (+1) (take q (drop (n+1) xs))
intmap = (take n xs) ++ [0] ++ plusoned ++ drop (n+1+q) xs
choose plyr
| (n + q == 6) = PlayerA
| otherwise = PlayerB
move (MancalaBoardImpl xs PlayerB) n
| ((isAllowedMove (MancalaBoardImpl xs PlayerB) n) == True) = (MancalaBoardImpl reswapsides (choose PlayerB))
| otherwise = error "Not an allowed move" where
swapsides = drop (length xs `div` 2) xs ++ take (length xs `div` 2) xs
performmove = getBoardData $ move (MancalaBoardImpl swapsides PlayerA) (n - (length xs `div` 2))
reswapsides = drop (length xs `div` 2) performmove ++ take (length xs `div` 2) performmove
choose plyr
| (n + (xs !! n) == 13) = PlayerB
| otherwise = PlayerA
{- gameOver checks to see if the game is over (i.e. if one player's side of the
- board is all empty -}
gameOver :: MancalaBoard -> Bool
gameOver board = (all (==0) (init (playerSide board PlayerA))) || (all (==0) (init (playerSide board PlayerB)))
{- winner returns a list of players who have the top score: there will only be
- one in the list if there is a clear winner, and none if it is a draw -}
winners :: MancalaBoard -> [Player]
winners board = filter g allPlayers
where g plyr
| (sum(playerSide board plyr) == maximum (mapsum board)) = True
| otherwise = False
mapsum board = map f allPlayers
f plyr = sum (playerSide board plyr)
---- show
instance Show MancalaBoard where
show (MancalaBoardImpl boardData player) =
-- (show boardData) ++ " " ++ (show player)
"Player A: " ++ (show (take ((length boardData) `div` 2) boardData)) ++ "\n" ++
"Player B: " ++ (show (drop ((length boardData) `div` 2) boardData)) ++ "\n" ++
"Current turn: " ++ (show player)
---- tests
testboard1 = MancalaBoardImpl [4,4,4,4,4,4,0,4,4,4,4,4,4,0] PlayerA
testboard2 = MancalaBoardImpl [0,1,2,3,4,5,6,5,5,5,5,0,0,7] PlayerB
testboard3 = MancalaBoardImpl [1,1,1,1,1,1,18,2,2,2,2,2,2,12] PlayerA
testboard4 = MancalaBoardImpl [0,1,0,2,0,3,6,5,0,10,0,15,0,21] PlayerB
testGetCurPlayer = (getCurPlayer testboard1 == PlayerA)
testGetBoardData = (getBoardData testboard2 == [0,1,2,3,4,5,6,5,5,5,5,0,0,7])
testPlayerSide = (playerSide testboard3 PlayerA == [1,1,1,1,1,1,18])
testNumCaptured = (numCaptured testboard4 PlayerB == 21)
testAllowedMoves = (allowedMoves testboard1 PlayerA == [0,1,2,3,4,5])
testIsAllowedMove = (isAllowedMove testboard2 0 == False)
testMove = (getCurPlayer(move testboard4 9) == PlayerA) && (getBoardData(move testboard4 9) == [1,2,1,3,1,4,6,5,0,0,1,16,1,22])
testGameOver = (gameOver testboard3 == False)
testWinners = (winners testboard1 == [PlayerA,PlayerB])
和
-- TwoPlayerMancala.hs
import MancalaBoard
main :: IO ()
main = do
putStrLn "Welcome! This program allows two people to play Mancala with each other."
putStrLn "For Player A, their pits are numbered 0, 1, 2, 3, 4, and 5. 6 is their store."
putStrLn "For Player B, their pits are numbered 7, 8, 9, 10, 11, and 12. 13 is their store."
putStrLn "In other words, this program represents a board that looks like this:"
putStrLn "[ ] [ 0] [ 1] [ 2] [ 3] [ 4] [ 5] [ 6]"
putStrLn "[13] [12] [11] [10] [ 9] [ 8] [ 7] [ ]"
putStrLn "Balls travel counterclockwise on this board."
putStrLn "To quit, enter \"quit\" at any point"
putStrLn "The game begins now."
playGame
playGame :: IO ()
playGame = do
putStrLn $ show initial
n <- getLine
let num = read n :: Int
makeMove initial num
makeMove board n = do
let board1 = move board n
putStrLn $ show board1
if (gameOver board1)
then endGame board1
else return ()
if (show (getCurPlayer board1) == "PlayerA") then putStrLn "Player A, please make your move"
else putStrLn "Player B, please make your move"
m <- getLine
if (m == "quit")
then endGame board1
else return ()
let mum = read m :: Int
makeMove board1 mum
endGame :: MancalaBoard -> IO ()
endGame board = do
putStrLn "The game is over! Here is the final board: "
putStrLn $ show board
putStrLn "The winner is: "
putStrLn $ show (winners board)
return ()
{-if ((winners board) == [PlayerA])
then let winner = "Player A" else
if ((winners board) == [PlayerB])
then let winner = "Player B" else
let winner = ""
putStrLn "The game is over! Here is the final board:"
putStrLn $ show board
if (winner == ("Player A" || "Player B"))
then putStrLn "The winner is " ++ winner
else putStrLn "The game was a tie!"-}
*编辑* 这是导致错误的完整输入和输出：
*Main> main
Welcome! This program allows two people to play Mancala with each other.
For Player A, their pits are numbered 0, 1, 2, 3, 4, and 5. 6 is their store.
For Player B, their pits are numbered 7, 8, 9, 10, 11, and 12. 13 is their store.
In other words, this program represents a board that looks like this:
[ ] [ 0] [ 1] [ 2] [ 3] [ 4] [ 5] [ 6]
[13] [12] [11] [10] [ 9] [ 8] [ 7] [ ]
Balls travel counterclockwise on this board.
To quit, enter "quit" at any point
The game begins now.
Player A: [4,4,4,4,4,4,0]
Player B: [4,4,4,4,4,4,0]
Current turn: PlayerA
2
Player A: [4,4,0,5,5,5,1]
Player B: [4,4,4,4,4,4,0]
Current turn: PlayerA
Player A, please make your move
5
Player A: [4,4,0,5,5,0,2]
Player B: [5,5,5,5,4,4,0]
Current turn: PlayerB
Player B, please make your move
8
Player A: [4,4,0,5,5,0,2]
Player B: [5,0,6,6,5,5,1]
Current turn: PlayerB
Player B, please make your move
12
Player A: [5,5,1,6,5,0,2]
Player B: [5,0,6,6,5,0,2]
Current turn: PlayerA
Player A, please make your move
1
Player A: [5,0,2,7,6,1,3]
Player B: [5,0,6,6,5,0,2]
Current turn: PlayerA
Player A, please make your move
5
Player A: [5,0,2,7,6,0,4]
Player B: [5,0,6,6,5,0,2]
Current turn: PlayerA
Player A, please make your move
4
Player A: [5,0,2,7,0,1,5]
Player B: [6,1,7,7,5,0,2]
Current turn: PlayerB
Player B, please make your move
7
*** Exception: Not an allowed move
答案 0 :(得分：2)
当我在第一个例子中用电路板替换initial时，我可以做到“7”就好了：
-- in MancalaBoard.hs
initial = MancalaBoardImpl [5,0,2,7,0,1,5,6,1,7,7,5,0,2] PlayerB
-- ghci TwoPlayerMancala.hs; main
...
The game begins now.
Player A: [5,0,2,7,0,1,5]
Player B: [6,1,7,7,5,0,2]
Current turn: PlayerB
7
Player A: [5,0,2,7,0,1,5]
Player B: [0,2,8,8,6,1,3]
Current turn: PlayerB
Player B, please make your move
换句话说，我无法复制错误？
（这是一个注释，直到我想要粘贴确切的输出。顺便说一下，你应该这样做。）
答案 1 :(得分：0)
您在命令行上测试的电路板比在TwoPlayerMancala.hs中测试的电路板不同。在命令行中，它是PlayerB，7是允许的移动。在您正在TwoPlayerMancala.hs进行测试的主板中，它是PlayerA轮次，允许移动为[0,1,2,3,4,5]。