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module Card where
import System.Random (RandomGen, random)
data Suit = Spade | Heart | Diamond | Club deriving (Show, Eq, Ord, Enum)
data Rank = Two | Three | Four | Five | Six | Seven | Eight
| Nine | Ten | Jack | Queen | King | Ace
deriving (Show, Eq, Ord, Enum)
data Card = Card { suit :: Suit, rank :: Rank } deriving (Show, Eq, Ord)
-- | Pretty print a card.
showCard :: Card -> String
showCard (Card st rk) = (show st) ++ " " ++ (rkStr)
where rkStr = case rk of
Jack -> "J"
Queen -> "Q"
King -> "K"
Ace -> "A"
_ -> show $ fromEnum rk + 2
-- | Produce one full 52-deck.
fullDeck = [Card st rk | st <- allSuits, rk <- allRanks]
where allSuits = enumFrom $ toEnum 0
allRanks = enumFrom $ toEnum 0
-- | Produce n full 52-decks.
fullDecks :: Int -> [Card]
fullDecks n = concat $ replicate n fullDeck
-- | Shuffle a list. Works by taking a random entry each time.
shuffle :: (RandomGen g) => g -> [a] -> [a]
shuffle _ [] = []
shuffle _ [x] = [x]
shuffle gen xs = (head right):(shuffle newGen (left ++ (tail right)))
where (rand, newGen) = random gen
i = rand `mod` (length xs)
(left, right) = splitAt i xs
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