src/advent13/advent13.hs

   1 {-# LANGUAGE OverloadedStrings #-}
   2
   3
   4 import Data.List
   5 import qualified Data.Set as S
   6
   7 data Cell = Empty | Horizontal | Vertical | Clockwise | Anticlockwise | Junction deriving (Show, Eq)
   8 data Direction = Up | Right | Down | Left deriving (Show, Eq, Ord, Enum, Bounded)
   9
  10 main :: IO ()
  11 main = do
  12     text <- TIO.readFile "data/advent12.txt"
  13     let (initial, rules) = successfulParse text
  14     let row = makeWorld 0 initial
  15     print $ part1 rules row
  16     print $ part2 rules row
  17
  18
  19
  20 -- Move in the current direction
  21 takeStep :: Direction -> Cell -> Int -> Int -> (Direction, Int, Int)
  22 takeStep Up x y = (x, y-1)
  23 takeStep Down x y = (x, y+1)
  24 takeStep Left x y = ( x-1, y)
  25 takeStep Right x y = (x+1, y)
  26
  27
  28 -- | a `succ` that wraps
  29 turnCW :: (Bounded a, Enum a, Eq a) => a -> a
  30 turnCW dir | dir == maxBound = minBound
  31            | otherwise = succ dir
  32
  33 -- | a `pred` that wraps
  34 turnACW :: (Bounded a, Enum a, Eq a) => a -> a
  35 turnACW dir | dir == minBound = maxBound
  36             | otherwise = pred dir
  37
  38
  39
  40 -- Parse the input file
  41
  42 type Parser = Parsec Void Text
  43
  44 sc :: Parser ()
  45 sc = L.space (skipSome spaceChar) CA.empty CA.empty
  46
  47 symb = L.symbol sc
  48 potP = (char '.' *> pure False) <|> (char '#' *> pure True)
  49
  50 initialPrefix = symb "initial state:"
  51 ruleSepP = symb "=>"
  52
  53 fileP = (,) <$> initialP <*> many ruleP
  54 initialP = initialPrefix *> many potP <* sc
  55 ruleP = Rule <$> ruleLHS <* ruleSepP <*> ruleRHS
  56 ruleLHS = count 5 potP <* sc
  57 ruleRHS = potP <* sc
  58
  59 successfulParse :: Text -> ([Bool], [Rule])
  60 successfulParse input =
  61         case parse fileP "input" input of
  62                 Left  _error -> ([], []) -- TIO.putStr $ T.pack $ parseErrorPretty err
  63                 Right world -> world