Solve day 4, part 1

Main.hs

@@ -3,9 +3,11 @@ module Main where
 import Day1 (day1)
 import Day2 (day2)
 import Day3 (day3)
+import Day4 (day4)
 
 main :: IO ()
 main = do
   day1
   day2
   day3
+  day4

src/Day4.hs

@@ -5,28 +5,27 @@ module Day4 (day4) where
 import Control.Applicative ((<|>))
 import Control.Monad (void)
 import qualified Data.Attoparsec.Text as P
+import qualified Data.Map as M
+import Data.Maybe (catMaybes)
+import qualified Data.Text as T
 
--- import qualified Data.Text as T
--- import qualified Data.Vector as V
--- import Numeric.Natural (Natural)
+type BYR = T.Text
 
-type BYR = String
+type IYR = T.Text
 
-type IYR = String
+type EYR = T.Text
 
-type EYR = String
+type HGT = T.Text
 
-type HGT = String
+type HCL = T.Text
 
-type HCL = String
+type ECL = T.Text
 
-type ECL = String
+type PID = T.Text
 
-type PID = String
+type CID = T.Text
 
-type CID = String
-
-data Passport = Passport
+data Passport = ValidPassport
   { byr :: BYR,
     iyr :: IYR,
     eyr :: EYR,
@@ -38,18 +37,39 @@ data Passport = Passport
   }
   deriving (Eq, Show)
 
-parsePassport :: P.Parser Passport
-parsePassport = do
-  -- parse pairs
-  pairs <- parsePair `P.sepBy` (void P.space <|> P.endOfLine)
-  undefined
-
-parsePair :: P.Parser (String, String)
-parsePair = do
+parserPair :: P.Parser (T.Text, T.Text)
+parserPair = do
   key <- P.count 3 P.letter
   _ <- P.char ':'
-  value <- P.many1 P.anyChar
-  return (key, value)
+  value <- P.takeWhile1 (P.inClass "a-zA-Z0-9#")
+  return (T.pack key, value)
+
+parserEntry :: P.Parser (M.Map T.Text T.Text)
+parserEntry = M.fromList <$> parserPair `P.sepBy` (void P.space <|> P.endOfLine)
+
+fromMap :: M.Map T.Text T.Text -> Maybe Passport
+fromMap m = do
+  byr <- m M.!? "byr"
+  iyr <- m M.!? "iyr"
+  eyr <- m M.!? "eyr"
+  hgt <- m M.!? "hgt"
+  hcl <- m M.!? "hcl"
+  ecl <- m M.!? "ecl"
+  pid <- m M.!? "pid"
+  return $ ValidPassport byr iyr eyr hgt hcl ecl pid (m M.!? "cid")
+
+parserPassport :: P.Parser (Maybe Passport)
+parserPassport = fromMap <$> parserEntry
+
+parseList :: String -> [Maybe Passport]
+parseList s =
+  let p = parserPassport `P.sepBy` P.endOfLine
+   in case P.parseOnly p (T.pack s) of
+        Left s -> error (show s)
+        Right r -> r
 
 day4 :: IO ()
-day4 = putStrLn "Day 4"
+day4 = do
+  r <- readFile "./input/day4"
+  putStr "[Day 4-1] # trees: "
+  print . length . catMaybes . parseList $ r