tasks a-s

Task/Playing-cards/Haskell/playing-cards.hs

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+import System.Random
+
+data Pip = Two | Three | Four | Five | Six | Seven | Eight | Nine | Ten |
+           Jack | Queen | King | Ace
+  deriving (Ord, Enum, Bounded, Eq, Show)
+
+data Suit = Diamonds | Spades | Hearts | Clubs
+  deriving (Ord, Enum, Bounded, Eq, Show)
+
+type Card = (Pip, Suit)
+
+fullRange :: (Bounded a, Enum a) => [a]
+fullRange = [minBound..maxBound]
+
+fullDeck :: [Card]
+fullDeck = [(pip, suit) | pip <- fullRange, suit <- fullRange]
+
+insertAt :: Int -> a -> [a] -> [a]
+insertAt 0 x ys     = x:ys
+insertAt n _ []     = error "insertAt: list too short"
+insertAt n x (y:ys) = y : insertAt (n-1) x ys
+
+shuffle :: RandomGen g => g -> [a] -> [a]
+shuffle g xs = shuffle' g xs 0 [] where
+  shuffle' g []     _ ys = ys
+  shuffle' g (x:xs) n ys = shuffle' g' xs (n+1) (insertAt k x ys) where
+    (k,g') = randomR (0,n) g