import Data.List
import Data.Function (on)
import Data.List (sortBy)

-- intial data type.
data KSItem = Object {itemmo :: Int
                        , weight :: Float
                        , profit :: Float
                        , itemname :: [Char]
                        } deriving (Show, Eq, Ord)

-- Function for turning intital data type into advanced data type.
devise :: KSItem -> FinKSItem
devise (Object i w p n ) = (XObject i w (p / w) n p)

-- function to sort on efficiency
sa = reverse(sortBy (compare `on` efficiency) (deviseAll tests))

-- The array of Objects
tests = [ (Object 1 4.13 1.4 "Weapon and Ammunition")
        ,(Object 2 2.13 2.74 "Water")
        ,(Object 3 3.03 1.55 "Pith Helmet")
        ,(Object 4 2.26 0.82 "Sun Cream")
        ,(Object 5 3.69 2.38 "Tent")
        ,(Object 6 3.45 2.93 "Flare Gun")
        ,(Object 7 1.09 1.77 "Olive Oil")
        ,(Object 8 2.89 0.53 "Firewood")
        ,(Object 9 1.08 2.77 "Kendal Mint Cake")
        ,(Object 10 3.23 4.29 "Snake Repellant Spray")
        ,(Object 11 2.29 2.85 "Bread")
        ,(Object 12 0.55 0.34 "Pot Noodles")
        ,(Object 13 2.82 (-0.45) "Software Engineering Textbook")
        ,(Object 14 2.31 2.17 "Tinned food")
        ,(Object 15 1.63 1.62 "Pork Pie")]

weights = [4.13, 2.13, 3.03, 2.26, 3.69, 3.45, 1.08, 2.89, 1.08, 3.23, 2.29, 0.55, 2.82, 2.31, 1.63]
values = [1.4, 2.74, 1.55, 0.82, 2.38, 2.93, 1.77, 0.53, 2.77, 4.29, 2.85, 0.34, (-0.45), 2.17, 1.62]
totalWeight = 20

    core x:xs p w | (w + (weight x)) > totalWeight core xs p w
        | core [] p w = p
        | otherwise (max a b)