todo

IO.hs

module IO where

import System.IO
import Control.Exception
import Control.DeepSeq
import Control.Monad.Trans.Either
import Control.Monad.Trans.Class
import Data.Either.Combinators
import System.Environment

failHint :: String -> EitherT SomeException IO a -> EitherT String IO a
failHint hint = bimapEitherT (\e -> hint ++ ": " ++ show e) id

parseArgs :: EitherT String IO (String, String)
parseArgs = do
    args <- lift getArgs
    let [inputFile, outputFile] = args
    failHint "Unable to parse args" $ EitherT $ try $ evaluate $ force (inputFile, outputFile)


parseInput :: String -> EitherT String IO (Int, Int, [[Int]])
parseInput content = do
    let ls = lines content
        n = (read $ ls !! 0) :: Int
        logCount = (read $ ls !! 1) :: Int
        grid = [ map read $ words row | row <- (drop 2 ls) ]
    failHint "Unable to parse content" $ EitherT $ try $ evaluate $ force (n, logCount, grid)

outputGrid :: Handle -> [[Int]] -> IO ()
outputGrid h grid = hPutStrLn h $ unlines [ unwords $ map show row | row <- grid ]

Main.hs

module Main where

import System.Environment
import System.IO
import Control.Monad.Trans.Either
import Control.Monad.Trans.Class
import IO
import Solution

-- TODO handle file open failure
main = do
    result <- runEitherT (do
        (inputFile, outputFile) <- parseArgs
        content <- lift $ readFile inputFile
        (n, logCount, grid) <- parseInput content
        lift $ putStrLn "Solving..."
        let solution = solve1 n logCount grid
        lift $ outputGrid stdout solution
        return ())

    case result of
        Right x -> putStrLn "Done"
        Left message -> hPutStrLn stderr $ "Error: " ++ message

Solution.hs

module Solution where

-- |Bruteforce version
solve1 :: Int -> Int -> [[Int]] -> [[Int]]
solve1 n logCount grid = grid -- TODO