---------- CSE P505 Final Exam, Autumn 2016 --------

-------------- provided type definitions (do not change) -----------

data Coin = Quarter | Dime | Nickel | Penny

-- Money q d n p is q quarters, d dimes, n nickels, and p pennies
data Money = Money Int Int Int Int

data MoneyTree = Leaf Coin | Node Coin MoneyTree MoneyTree

------------------- Problem 7 ----------------------------

-- (no provided code)

------------------- Problem 8 --------------------


{-
main8 =  -- some tests; see also the commented out main8 at bottom of file
  do {
    printMoney (Money 2 4 6 8) ; putStr "\n" ;
    printMoney (Money 2 0 2 0) ; putStr "\n" ;
    printMoney (Money 0 0 0 0) ; putStr "\n" 
  }
-}
------------------- Problem 9 --------------------

instance Eq Money where
  (==) (Money q1 d1 n1 p1) (Money q2 d2 n2 p2) =
    q1 == q2 && d1 == d2 && n1 == n2 && p1 == p2

-- reduce_pennies_to_half is written as intended for the exam;
-- do not change it even if you really want to
reduce_pennies_to_half (Money q d n p) =
  Money q d n (if (q + d + n) `div` p >= 1 then q + d + n else p)

main9 = -- some tests referred to in 9b and 9c
  do {
    print ((Money 2 3 4 15) == (Money 4 0 1 0))  ;
    print ((Money 2 3 4 15) == (Money 2 3 4 15)) ;
    print (reduce_pennies_to_half (Money 2 3 4 15)
            == reduce_pennies_to_half (Money 4 0 1 0)) ;
    print (reduce_pennies_to_half (Money 2 3 4 15)
            == reduce_pennies_to_half (Money 2 3 4 15)) ;
  }

-------------------- main ---------------------

main = do {
         return () ;
--         main8 ;
         main9
       }