尝试发出 HTTP 请求时，出现错误：
{-# LANGUAGE OverloadedStrings #-}
import Network.HTTP.Conduit -- the main module
-- The streaming interface uses conduits
import Data.Conduit
import Data.Conduit.Binary (sinkFile)
import qualified Data.ByteString.Lazy as L
import Control.Monad.IO.Class (liftIO)
main :: IO ()
main = do
simpleHttp "http://www.example.com/foo.txt" >>= L.writeFile "foo.txt"
错误是：
Couldn't match type `L.ByteString'
with `bytestring-0.10.0.2:Data.ByteString.Lazy.Internal.ByteString'
Expected type: bytestring-0.10.0.2:Data.ByteString.Lazy.Internal.ByteString
-> IO ()
Actual type: L.ByteString -> IO ()
In the return type of a call of `L.writeFile'
In the second argument of `(>>=)', namely `L.writeFile "foo.txt"'
In a stmt of a 'do' block:
simpleHttp "http://www.example.com/foo.txt"
>>= L.writeFile "foo.txt"
我无法弄清楚如何解决它，因为错误的文本并没有真正的意义。