我正在尝试完成以下任务：

slice :: Int -> Int -> [a] -> [a]
slice from to xs = take (to - from + 1) (drop from xs)

trimBoard :: Board -> Int -> Board
trimBoard s y = slice ((y*3)) (((y+1)*3)-1) s

getBox :: Board -> Int -> Int -> [Sequence]
getBox s y x = [ (trimBoard c x) | c <- (trimBoard s y)]

具体来说，我正在尝试运行一个函数，获取结果[[int]]，然后将另一个函数映射到该结果。哪个haskell似乎很令人讨厌，我需要使用“ lambda函数”和我完全无法阅读或理解的其他向导的某种组合来实现这一点。

有没有简单的方法可以不需要7个月的数学函数语法课程？

如上所述，结果board是[[int]]，而序列只是[int]。

它产生的错误是

sudoku.hs:139:19: error:
    • Couldn't match type ‘[Int]’ with ‘Int’
      Expected type: Sequence
        actual type: Board
    • In the expression: (trimBoard c x)
      In the expression: [(trimBoard c x) | c <- (trimBoard s y)]
      In an equation for ‘getBox’:
          getBox s y x = [(trimBoard c x) | c <- (trimBoard s y)]

sudoku.hs:139:29: error:
    • Couldn't match type ‘Int’ with ‘[Int]’
      Expected type: Board
        actual type: Sequence
    • In the first argument of ‘trimBoard’,namely ‘c’
      In the expression: (trimBoard c x)
      In the expression: [(trimBoard c x) | c <- (trimBoard s y)] Failed,modules loaded: none.