Haskell中的参数hGetContents无效

Question

I'm trying to sort a list of ints and print them out, but am receiving this exception:

Exception: <stdin>: hGetContents: invalid argument (Bad file descriptor)

The program:

import Data.List

main :: IO ()
main = do
    interact maxTri
    putStrLn ""

readInt :: String -> Int
readInt = read

maxTri :: String -> String
maxTri = show .
    sort .
    map readInt .
    words

Answer 1

interact (semi-)closes the input stream. This does not play well if you are in ghci, which expects to continue using the input stream.

Compile and run your program with

ghc path.hs
path

and this problem should not appear.