day 9++

src/day09/Day9Lib.hs

@@ -1,3 +1,5 @@
+{-# LANGUAGE InstanceSigs #-}
+
 module Day9Lib
   ( Rope (..),
     newRope,
@@ -12,43 +14,47 @@ where
 import Data.List
 import Debug.Trace
 
-type Vector = (Int, Int)
-
--- data Rope = Rope Vector Vector deriving (Show, Eq)
-data Rope = Rope [Vector] deriving (Show, Eq)
+newtype Vector = Vector (Int, Int) deriving (Show, Eq)
 
-plus :: Vector -> Vector -> Vector
-(x1, y1) `plus` (x2, y2) = (x1 + x2, y1 + y2)
+instance Num Vector where
+  (+) :: Vector -> Vector -> Vector
+  Vector v1 + Vector v2 = Vector (fst v1 + fst v2, snd v1 + snd v2)
+  (-) :: Vector -> Vector -> Vector
+  Vector v1 - Vector v2 = Vector (fst v1 - fst v2, snd v1 - snd v2)
+  (*) :: Vector -> Vector -> Vector
+  Vector v1 * Vector v2 = Vector (fst v1 * fst v2, snd v1 * snd v2)
+  fromInteger :: Integer -> Vector
+  fromInteger i = Vector (fromInteger i, fromInteger i)
+  abs :: Vector -> Vector
+  abs (Vector v) = Vector (abs . fst $ v, abs . snd $ v)
+  signum :: Vector -> Vector
+  signum (Vector (x, y)) = Vector (signum x, signum y)
 
-minus :: Vector -> Vector -> Vector
-(x1, y1) `minus` (x2, y2) = (x1 - x2, y1 - y2)
+newtype Rope = Rope [Vector] deriving (Show, Eq)
 
 stimes :: Int -> Vector -> Vector
-m `stimes` (x, y) = (m * x, m * y)
-
-vl1 :: Vector -> Int
-vl1 (x, y) = abs x + abs y
+m `stimes` v = (fromInteger . toInteger) m * v
 
 vlinf :: Vector -> Int
-vlinf (x, y) = max (abs x) (abs y)
+vlinf v = let Vector (ax, ay) = abs v in max ax ay
 
 vtruncate :: Vector -> Vector
-vtruncate (x, y) = (signum x * min 1 (abs x), signum y * min 1 (abs y))
+vtruncate v = let Vector (ax, ay) = abs v in signum v * Vector (min 1 ax, min 1 ay)
 
 newRope :: Int -> Rope
-newRope l = Rope $ replicate l (0, 0)
+newRope l = Rope $ replicate l (Vector (0, 0))
 
 move :: Vector -> Char -> Int -> Vector
-move v 'L' d = v `plus` (d `stimes` (-1, 0))
-move v 'R' d = v `plus` (d `stimes` (1, 0))
-move v 'U' d = v `plus` (d `stimes` (0, 1))
-move v 'D' d = v `plus` (d `stimes` (0, -1))
+move v 'L' d = v + (d `stimes` (Vector (-1, 0)))
+move v 'R' d = v + (d `stimes` (Vector (1, 0)))
+move v 'U' d = v + (d `stimes` (Vector (0, 1)))
+move v 'D' d = v + (d `stimes` (Vector (0, -1)))
 move v dir d = error $ "wrong direction:" ++ show dir
 
 follow :: Vector -> Vector -> [Vector] -> (Vector, [Vector])
 follow h t hist
-  | vlinf (h `minus` t) >= 2 =
-      let newt = (t `plus` vtruncate (h `minus` t))
+  | vlinf (h - t) >= 2 =
+      let newt = (t + vtruncate (h - t))
        in follow h newt (newt : hist)
   | otherwise = (t, hist)
 
@@ -67,7 +73,7 @@ moveRope _ _ = error "rope too short"
 -- ####################
 
 processInput1 :: String -> Int
-processInput1 = length . nub . snd . foldl processLine1 (newRope 2, [(0, 0)]) . lines
+processInput1 = length . nub . snd . foldl processLine1 (newRope 2, [Vector (0, 0)]) . lines
 
 processLine1 :: (Rope, [Vector]) -> String -> (Rope, [Vector])
 processLine1 (r@(Rope (h : t : [])), hist) (dir : _ : dist) =
@@ -77,7 +83,7 @@ processLine1 (r@(Rope (h : t : [])), hist) (dir : _ : dist) =
 processLine1 _ s = error $ "processline1 error: " ++ show s
 
 processInput2 :: String -> Int
-processInput2 = length . nub . snd . foldl processLine2 (newRope 10, [(0, 0)]) . lines
+processInput2 = length . nub . snd . foldl processLine2 (newRope 10, [Vector (0, 0)]) . lines
 
 processLine2 :: (Rope, [Vector]) -> String -> (Rope, [Vector])
 processLine2 (r@(Rope (h : ks)), hist) (dir : _ : dist) =