module Template_03(prodList, squareSecond, List(..), 
  eval, convert, normalize, listToExpr, Expr(..)) where

-- Exercise 2

data Brand = Audi | BMW | Fiat | Lamborghini deriving Show
data Vehicle =
    Car Brand Double -- horsepower
  | Bicycle
  | Truck Int -- number of wheels
  deriving Show

data List = Cons Integer List | Empty deriving Show

validVehicle :: Vehicle -> Bool
validVehicle = undefined

prodList :: List -> Integer
prodList = undefined

squareSecond :: List -> List
squareSecond = undefined 


-- Exercise 3

data Expr =
    Number Integer
  | Plus Expr Expr
  | Negate Expr
  deriving Show

eval :: Expr -> Integer
eval (Number x) = x
eval (Plus e1 e2) = eval e1 + eval e2
eval (Negate e) = - eval e

ite True x y = x
ite False x y = y

convert :: Expr -> Expr
convert = undefined

normalize :: Expr -> Expr
normalize = undefined

listToExpr :: List -> Expr
listToExpr = undefined