haskell：將兩個數組合併成一個Data array

Question

請問你能幫我跟下面嗎？我有2個數組，我需要合併成一個數組數組。下面的代碼不會合並，但它會創建一個笛卡爾...

我想有以下的輸出：

data DataXY = DataXY { 
    var1 :: String, 
    var2 :: String 
} deriving (Eq, Show) 

parse :: [DataXY] 
parse = x 
    where 
     x = [DataXY v1 v2 | v1 <- arr1, v2 <- arr2] 
      where 
       arr1 = ["x1", "x2", "x3"] 
       arr2 = ["y1", "y2", "y3"] 

感謝

DataXY {var1 = "x1", var2 = "y1"}, 
DataXY {var1 = "x2", var2 = "y2"}, 
DataXY {var1 = "x3", var2 = "y3"} 

---代碼， 米。

Answer 1

zipWith是你想要的這裏

parse :: [DataXY] 
parse = zipWith DataXY arr1 arr2 
    where arr1 = ["x1", "x2", "x3"] 
     arr2 = ["y1", "y2", "y3"] 

Answer 2

郵編兩個列表，以避免笛卡爾乘積：

parse :: [DataXY] 
parse = x 
    where 
     x = [DataXY v1 v2 | (v1,v2) <- zip arr1 arr2] 
      where 
       arr1 = ["x1", "x2", "x3"] 
       arr2 = ["y1", "y2", "y3"] 

隨着GHC你可以-XParallelListComp實現並行列表理解，寫

parse :: [DataXY] 
parse = x 
    where 
     x = [DataXY v1 v2 | v1 <- arr1 | v2 <- arr2 ] 
      where 
       arr1 = ["x1", "x2", "x3"] 
       arr2 = ["y1", "y2", "y3"]