#2 Polish CardDeck

lib/CardDeck.hs

@@ -1,17 +1,31 @@
 module CardDeck
 ( Card
-, CardStatus(..)
+, CardType (..)
+, CardValue (..)
+, CardStatus (..)
 , Stack
 
 , generateDeck
 , generateShuffledDeck
+
 , showCard
 , hideCard
 , flipCard
+, matchType
+, matchValue
+, matchColor
 ) where
 
 import Shuffle
 
+----------------------------------------------------------------------
+-- Representation of the Standard 52-card deck.                     --
+-- Extra support for handling piles of cards, hiding and showing    --
+-- cards and checking if two match given a property.                --
+----------------------------------------------------------------------
+
+----------------------------- Constants ------------------------------
+
 -- Colors of cards
 data CardType = Clubs
               | Diamonds
@@ -39,7 +53,7 @@ data CardValue = Ace
 
 data CardStatus = Hidden
                 | Visible
-                deriving (Show)
+                deriving (Show, Eq)
 
 -- A card has a type and a value and is either shown or hidden.
 type Card = (CardType, CardValue, CardStatus)
@@ -47,21 +61,40 @@ type Card = (CardType, CardValue, CardStatus)
 -- A stack of cards
 type Stack = [Card]
 
--- Generate a standard 52-card deck, given by CardValue and CardType
+----------------------------------------------------------------------
+
+-- Generate a standard 52-card deck, with values by CardValue and types
+-- by CardType. Cards are hidden by default.
 generateDeck :: Stack
 generateDeck = [(cType, cValue, Hidden) | cType <- types, cValue <- values]
     where types  = init $ enumFrom Clubs
           values = init $ enumFrom Ace 
 
+-- Generate a standard 52-card deck and shuffle all cards randomly.
 generateShuffledDeck :: Stack
 generateShuffledDeck = shuffle generateDeck
 
+-- Show a card.
 showCard :: Card -> Card
 showCard (t, v, _) = (t,v,Visible)
 
+-- Hide a card.
 hideCard :: Card -> Card
 hideCard (t, v, _) = (t,v,Hidden)
 
+-- Flip the card. If it was visible, it is now hidden and vice versa.
 flipCard :: Card -> Card
 flipCard c@(_, _, Visible) = hideCard c
 flipCard c@(_, _, Hidden)  = showCard c
+
+-- Check if two cards match type.
+matchType :: Card -> Card -> Bool
+matchType (t1, _, _) (t2, _, _) = t1 == t2
+
+-- Check if two cards match color.
+matchValue :: Card -> Card -> Bool
+matchValue (_, v1, _) (_, v2, _) = v1 == v2
+
+-- Check if two cards have the same color.
+matchColor :: Card -> Card -> Bool
+matchColor (t1, _, _) (t2, _, _) = t1 == t2 || (fromEnum t1 + fromEnum t2) `elem` [3, 6]