[Haskell-cafe] After `readFile`, why cannot i `writeFile` ?

[zaxis]

Bill Atkins-6 wrote:
> 
> readFile reads the file lazily so it isn't closed until the entire
> contents have been consumed.
> 
> Try System.IO.Strict.readFile, which will read the entire file at once.
> Yes, and i can use appendFile too.
> 
> appendFile "ssqHitNum.txt" $ unwords $ [no] ++ map (\n -> show n) hitNum
> ++ ["\n"]
> 
> zaxis <z_axis at 163.com> writes:
> 
>> hitSSQ :: String -> [Int] -> IO ()
>> hitSSQ no hitNum = do
>>    let newNum = unwords $ [no] ++ map (\n -> show n) hitNum
>>    hitNums <- fmap lines $ readFile "test.txt"
>>    writeFile "test.txt" $ unlines $ hitNums ++ [newNum]
>> 
>> *** Exception: test.txt: openFile: resource busy (file is locked)
> 
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