haskell readIO用法及代碼示例

Haskell語言Prelude模塊中函數readIO的用法及代碼示例。

用法類型：

Read a => String -> IO a

示例1：

源碼：


main = do x <- rList "[1,3,5,7]"
	  y <- rInt  "5"
	  print (map (y*) x)

rList :: String -> IO [Int]
rList = readIO

rInt :: String -> IO Int
rInt = readIO

輸出：

[5,15,25,35]

示例2：

源碼：


main = do x <- aaa "[1,3,5,7]"
	  print x
	  
aaa :: String -> IO (Int,Int,[Int])	  
aaa str = do x <- readIO str
	     return (sum x, product x, x)

輸出：

(16,105,[1,3,5,7])

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