hackerrank--- challenges/fp-update-list

纯属为了练习haskell，　竟然贴代码都没办法高亮。

Update the values of a list with their absolute values. The input and output portions will be handled automatically during grading. You only need to write a function with the recommended method signature.

Input Format
There are N integers, each on a new line. These are the N elements of the input array.

Output Format
N integers each on a new line; these are the absolute values of the input list, in that order.

Sample Input
2
-4
3
-1
23
-4
-54
Sample Output
2
4
3
1
23
4
54

Accpeted Code:

1 -- Enter your code here. Read input from STDIN. Print output to STDOUT
2 
3 f arr = [if x >= 0 then x else -x | x <- arr] -- Complete this function here
4 
5 -- This section handles the Input/Output and can be used as it is. Do not modify it.
6 main = do
7    inputdata <- getContents
8    mapM_ putStrLn $ map show $ f $ map (read :: String -> Int) $ lines inputdata