{- 6.827 Problem Set 2, Problem 4 Replace these lines with the names of your team members Please do not remove this initial comment or alter the first or last line. -} module Main(main) where type Poly = [(Int,Int)] -- Part A addPoly :: Poly -> Poly -> Poly -- Part B mulPoly :: Poly -> Poly -> Poly -- Part C evalPoly :: Poly -> Int -> Int -- Test code and useful utilities showPoly :: Poly -> String showPoly [] = "0" showPoly xs = foldr1 plusGlue (map showTerm xs) "" where plusGlue as bs r = as \$ showString " + " \$ bs r showTerm (c,n) r = shows c \$ showExp n r showExp 0 r = r showExp 1 r = showString "x" r showExp n r = showString "x^" \$ shows n r x :: Poly nx :: Poly xPlus1 :: Poly xLess1 :: Poly xPlus2 :: Poly nxLess1 :: Poly x = [(1,1)] nx = [(-1,1)] xPlus1 = (1,0):x xLess1 = (-1,0):x xPlus2 = (2,0):x nxLess1 = (-1,0):nx main = let zero = addPoly x nx one = addPoly nx xPlus1 p2xp3 = addPoly xPlus1 xPlus2 x2p2xp1 = mulPoly xPlus1 xPlus1 x2p1 = mulPoly xPlus1 xLess1 nx2m2xm1= mulPoly xPlus1 nxLess1 x3p3x2p3xp1 = mulPoly x2p2xp1 xPlus1 zero' = addPoly x2p2xp1 nx2m2xm1 zero'' = mulPoly zero' x3p3x2p3xp1 printPoly = putStrLn . showPoly in print zero >> printPoly one >> printPoly p2xp3 >> printPoly x2p2xp1 >> printPoly x2p1 >> printPoly nx2m2xm1 >> printPoly x3p3x2p3xp1 >> printPoly zero' >> printPoly zero''>> print (evalPoly zero 17) >> print (evalPoly p2xp3 (-1)) >> print (evalPoly x3p3x2p3xp1 (-1))