Small refactoring

src/Day01.hs

@@ -17,18 +17,22 @@ similarityScore xs ys =
   let elemsY = [(fst . fromJust $ uncons y, length y) | y <- (group . sort) ys]
    in sum [x * snd y | x <- xs, y <- elemsY, x == fst y]
 
-day01_1 :: IO ()
-day01_1 = do
+parseInput :: IO [[Int]]
+parseInput = do
   contents <- lines <$> readFile "input/day1.txt"
   let [x, y] = transpose $ map read . words <$> contents
+  return [x, y]
+
+day01_1 :: IO ()
+day01_1 = do
+  [x, y] <- parseInput
   putStrLn $
     "Day 1, Puzzle 1 solution: "
       ++ show (listDistance x y)
 
 day01_2 :: IO ()
 day01_2 = do
-  contents <- lines <$> readFile "input/day1.txt"
-  let [x, y] = transpose $ map read . words <$> contents
+  [x, y] <- parseInput
   putStrLn $
     "Day 1, Puzzle 2 solution: "
       ++ show (similarityScore x y)