day04/guards.hs

   1 import qualified Data.Map.Strict as M
   2 import Text.ParserCombinators.ReadP
   3 import Control.Applicative ((<|>))
   4
   5 main :: IO ()
   6 main = do
   7     shifts <- map parse . lines <$> getContents
   8     print "a"
   9
  10 type GID = Int
  11
  12 data Status = Begin | Awake | Asleep deriving (Show)
  13 data Date = Date Int Int Int deriving (Show)
  14 data Time = Time Int Int deriving (Show)
  15
  16 data Shift = Shift Status GID Date Time deriving (Show)
  17
  18 parse :: String -> Shift
  19 parse = fst . head . readP_to_S go
  20     where digit :: ReadP Char
  21           digit = satisfy (\char -> char >= '0' && char <= '9')
  22           stGet :: String -> Status
  23           stGet "wakes up" = Awake
  24           stGet "falls asleep" = Asleep
  25           stGet "Guard #" = Begin
  26           go :: ReadP Shift
  27           go = do
  28             char '['
  29             year <- read <$> count 4 digit
  30             char '-'
  31             month <- read <$> count 2 digit
  32             char '-'
  33             day <- read <$> count 2 digit
  34             char ' '
  35             hour <- read <$> count 2 digit
  36             char ':'
  37             minute <- read <$> count 2 digit
  38             string "] "
  39             rt <- string "Guard #" <|> string "wakes up" <|> string "falls asleep"
  40             gid <- option (-1) (read <$> many1 digit)
  41             optional $ string " begins shift"
  42             eof
  43             let d = Date year month day
  44             let t = Time hour minute
  45             return (Shift (stGet rt) gid d t)