输入'|'上的Haskell解析错误

Question

我收到以下错误:

输入'|'解析错误

用我的代码:

makeMove :: Player -> Board -> Maybe Board
makeMove p b | hasWinner b == Nothing = getMove p rb ri
                                        where rb = gameTree p b
                                              ri = minimax p rb
                                              ros2int (i' :> ri') = i'
                                              rb2b (b':rbs') = b
                                              getMove p (r:rs) (i:is) = let bs  = map rb2b rs
                                                                            is  = map ros2int is
                                                                            idx = elemIndex (maximum' is) is
                                                                            res (Nothing) = Nothing
                                                                            res (Just x) = Just ((bs)!!x)
                                                                        in res idx
              | otherwise = Nothing

但是我认为这通常是由标签干扰引起的,但是我检查过,我只使用了空格,所以这不是问题所在.任何人都可以帮我解决这个问题吗？

提前致谢!

最好的问候,Skyfe.

Answer 1

该where条款应该是所有警卫:

fun a b 
  | one = ...
  | oterwise = ...
  where ....