step_4_build_custom_decks.hs

-- Step 4: Build Custom Decks

data Suit = Club | Diamond | Heart | Spade
    deriving (Read, Show, Enum, Eq, Ord, Bounded)

data CardValue = Two | Three | Four
     | Five | Six | Seven | Eight | Nine | Ten
     | Jack | Queen | King | Ace
    deriving (Read,  Show, Enum, Eq, Ord, Bounded)

data Card = Card { value :: CardValue,
                    suit :: Suit }
    deriving (Read, Show, Eq, Bounded)

instance Ord Card where
    compare c1 c2 = compare (value c1, suit c1) (value c2, suit c2)

instance Enum Card where
    toEnum n  = let (v,s) = n `divMod` 4 in Card (toEnum v) (toEnum s)
    fromEnum c = fromEnum (value c) * 4 + fromEnum (suit c)

type Deck = [Card]

deck :: Deck
deck = [Card val su | val <- [Two .. Ace], su <- [Club .. Spade]]

-- Here's our function for building a custom deck
buildDeck :: Card -> Card -> Deck
buildDeck lowestCard highestCard = [ lowestCard .. highestCard ]