advent of code 2022 day 2

A200.hs

module A200 where
import Data.List.Split (splitOn)

data Symbol = Rock | Paper | Scissors
data Strategy = Win | Lose | Draw
data Match = Match { opponent :: Symbol, player :: Symbol }

strategy :: Symbol -> Strategy -> Match
strategy o s = Match o (case s of
    Win -> case o of
        Rock -> Paper
        Paper -> Scissors
        Scissors -> Rock
    Lose -> case o of
        Rock -> Scissors
        Paper -> Rock
        Scissors -> Paper
    Draw -> o)

score :: Match -> Int
score (Match Rock Rock) = 4
score (Match Rock Paper) = 8
score (Match Rock Scissors) = 3
score (Match Paper Rock) = 1
score (Match Paper Paper) = 5
score (Match Paper Scissors) = 9
score (Match Scissors Rock) = 7
score (Match Scissors Paper) = 2
score (Match Scissors Scissors) = 6

instance Show Symbol where
    show Rock = "Rock"
    show Paper = "Paper"
    show Scissors = "Scissors"

instance Show Match where
    show (Match o p) = show o ++ " vs " ++ show p

instance Read Symbol where
    readsPrec _ "A" = [(Rock, "")]
    readsPrec _ "X" = [(Rock, "")]
    readsPrec _ "B" = [(Paper, "")]
    readsPrec _ "Y" = [(Paper, "")]
    readsPrec _ "C" = [(Scissors, "")]
    readsPrec _ "Z" = [(Scissors, "")]
    readsPrec _ _ = []

instance Read Strategy where
    readsPrec _ "X" = [(Lose, "")]
    readsPrec _ "Y" = [(Draw, "")]
    readsPrec _ "Z" = [(Win, "")]
    readsPrec _ _ = []

input = "/Users/justin/Documents/advent/advent101/input201"

parseMatch :: String -> Match
parseMatch (o:_:p:_) = Match (read [o]) (read [p])

parseStrategy :: String -> Match
parseStrategy (o:_:s:_) = strategy (read [o]) (read [s])

a201 :: IO ()
a201 = readFile input >>= print . sum . map (score. parseMatch) . lines

a202 :: IO ()
a202 = readFile input >>= print . sum . map (score . parseStrategy) . lines