Part 1 done, 2 in process

day4/app/Main.hs

@@ -1,5 +1,36 @@
 module Main where
 
+import Data.HashSet (HashSet)
+import qualified Data.HashSet as HS
+import Data.List.Split (splitOn)
+
+partOne :: String -> Int
+partOne = sum . map computePoints . filter (not . null) . map partOnePerLine . lines
+
+partOnePerLine :: String -> [Int]
+partOnePerLine = hashIntersect . strToInt . beforeHashSet
+
+computePoints :: [Int] -> Int
+computePoints n = 2 ^ (length n - 1)
+
+hashIntersect :: (HashSet Int, HashSet Int) -> [Int]
+hashIntersect (x, y) = HS.toList (HS.intersection x y)
+
+strToInt :: (String, String) -> (HashSet Int, HashSet Int)
+strToInt (win, cards) = ((HS.fromList . map getInt . words) win, (HS.fromList . map getInt . words) cards)
+
+getInt :: String -> Int
+getInt n = read n :: Int
+
+beforeHashSet :: String -> (String, String)
+beforeHashSet = (\v -> (head v, last v)) . splitOn "|" . last . splitOn ":"
+
+partTwoPerLine :: String -> Int
+partTwoPerLine = length . partOnePerLine
+
 main :: IO ()
 main = do
-  putStrLn "Hello, Haskell!"
+  content <- readFile "sample.txt"
+  (print . partOne) content
+  let tmp = (zip [1 ..] . map partTwoPerLine . lines) content
+  mapM_ print tmp