Haskell IO传递给另一个函数

Question

这个问题与此有关 Haskell Input Return Tuple

我想知道如何将monad IO的输入传递给另一个函数以进行一些计算。

其实我想要的是

-- First Example
test = savefile investinput 
-- Second Example
maxinvest :: a
maxinvest = liftM maximuminvest maxinvestinput

maxinvestinput :: IO()
maxinvestinput = do
    str <- readFile "C:\\Invest.txt"
    let cont = words str
    let mytuple = converttuple cont
    let myint = getint mytuple

    putStrLn ""

-- Convert to Tuple
converttuple :: [String] -> [(String, Integer)]
converttuple [] = []
converttuple (x:y:z) = (x, read y):converttuple z

-- Get Integer
getint :: [(String, Integer)] -> [Integer]
getint [] = []
getint (x:xs) = snd (x) : getint xs

-- Search Maximum Invest
maximuminvest :: (Ord a) => [a] -> a
maximuminvest [] = error "Empty Invest Amount List"
maximuminvest [x] = x
maximuminvest (x:xs)   
     | x > maxTail = x  
     | otherwise = maxTail  
     where maxTail = maximuminvest xs 

在第二个示例中，从文件中读取maxinvestinput并将数据转换为期望的类型maximuminvest。 请帮忙。

感谢。

Answer 1

Answer 2

我不确定我理解你的问题，但我会尽我所能回答。如果我理解正确的话，我已经简化了一些事情以获得问题的“肉”。

maxInvestInput :: IO [Integer]
maxInvestInput = liftM convertToIntegers (readFile "foo")

maximumInvest :: Ord a => [a] -> a
maximumInvest = blah blah blah

main = do
   values <- maxInvestInput
   print $ maximumInvest values

OR

main = liftM maximumInvest maxInvestInput >>= print