gistfile1.txt

module Main where


-- DAY 4
import Control.Applicative hiding (some, many)
import Control.Monad
import Data.Void
import Text.Megaparsec hiding (State)
import Text.Megaparsec.Char
import qualified Text.Megaparsec.Char.Lexer as L

requiredFields = [
        "byr",
        "iyr",
        "eyr",
        "hgt",
        "hcl",
        "ecl",
        "pid"]

type Parser = Parsec Void String
type Passport = [(String, String)]

main = do
  fileContent <- readFile "day4.txt"
  let result = numOfValidPassports $ parseMaybe (many passport) fileContent
  print result

numOfValidPassports :: Maybe [Passport] -> Int
numOfValidPassports Nothing = 0
numOfValidPassports (Just pps) = sum $ map fromEnum $ map isValid pps

isValid :: Passport -> Bool
isValid passport =
  all (\x -> x `elem` fields) requiredFields
  where
    fields = fmap fst passport

section :: Parser (String, String)
section = do
  field <- some letterChar
  void $ char ':'
  value <- some (alphaNumChar <|> char '#')
  void spaceChar <|> eof
  return (field, value)

passport :: Parser Passport
passport = do
  content <- some section
  (void $ char '\n') <|> eof
  return content