Rock-paper-scissors: Difference between revisions

=={{header|Haskell}}==

<lang haskell>import System.Random

data Choice = Rock | Paper | Scissors

deriving (Show, Eq)

res x y | x == y = "draw"

res Paper Rock = "player wins"

res Scissors Paper = "player wins"

res Rock Scissors = "player wins"

res _ _ = "player loses"

genrps (r,p,s) = fmap rps rand

where rps x | x <= s = Rock

| x <= s+r = Paper

| otherwise = Scissors

rand = randomRIO (1,r+p+s) :: IO Int

getrps = fmap rps getLine

where rps "scissors" = Scissors

rps "rock" = Rock

rps "paper" = Paper

rps _ = error "invalid input"

game (r,p,s) = do putStrLn "rock, paper or scissors?"

h <- getrps

c <- genrps (r,p,s)

putStrLn ("Player: " ++ show h ++ " Computer: " ++ show c)

putStrLn (res h c ++ "\n")

let rr = if h == Rock then r + 1 else r

pp = if h == Paper then p + 1 else p

ss = if h == Scissors then s + 1 else s

game (rr,pp,ss)

main = game (1,1,1)</lang>