Haskell：调用列表中每个元素的函数

Question

I am making a sudoku solving program and I have a potentialNbrsAt function that gets the numbers that could be at position x y.

Now, I am trying to get the intersect of each lists of potential numbers in a column. Something like the onlyOnePlaceForNbrInCol function bellow.

Code:

potentialNbrsAt :: Int -> Int -> Sudoku -> [Int]
potentialNbrsAt x y sudoku = intersect rowMissingNbrs $ intersect colMissingNbrs sqrMissingNbrs
                where rowMissingNbrs = getMissingNbrs $ getRow y sudoku
                      colMissingNbrs = getMissingNbrs $ getCol x sudoku
                      sqrMissingNbrs = getMissingNbrs $ getSquare squareIndex sudoku
                      squareIndex    = 3 * (y `div` 3) + (x `div` 3)

onlyOnePlaceForNbrInCol :: Int -> Int -> Sudoku -> Bool
onlyOnePlaceForNbrInCol colIndex nbr sudoku = -- What goes here? Some pointers please???

I think onlyOnePlaceForNbrInCol should, at some point, call potentialNbrsAt with each numbers from 0 to 8 as an argument for y. Telling me how to do this would greatly help.

Answer 1

因此，您试图确定是否所有数字[0..8]满足给定的谓词。

Answer 2

What about [ potentialNbrsAt xy sudoku | y <- [0..8] ] [ potentialNbrsAt xy sudoku | y <- [0..8] ] ? This gives you a list of all the results for such values of y .