Day 4

day04/Commons.hs

@@ -0,0 +1,28 @@
+module Commons where
+
+import Data.List.Utils (split)
+import GHC.IO.Handle (isEOF)
+
+
+data Card = Card { cid :: Int, nCopies :: Int, winningNumbers :: [Int], numbers :: [Int] } deriving (Show)
+
+
+parseNumbers :: String -> [Int]
+parseNumbers [] = []
+parseNumbers (' ': n1: n2: t) = read [n1, n2]: parseNumbers t
+
+parseCard :: String -> Card
+parseCard ('C': 'a': 'r': 'd': ' ': i1: i2: i3: ':': t) = let (rawWN: rawN: _) = split " |" t
+                                                          in Card {cid = read [i1, i2, i3],
+                                                                   nCopies = 1,
+                                                                   winningNumbers = parseNumbers rawWN,
+                                                                   numbers = parseNumbers rawN}
+
+parse :: IO [Card]
+parse = do done <- isEOF
+           if done
+              then return []
+              else do line <- getLine
+                      let card = parseCard line
+                      otherCards <- parse
+                      return (card: otherCards)