A-M baby

Task/Fibonacci-sequence/Haskell/fibonacci-sequence-4.hs

@@ -0,0 +1,15 @@
+import Data.List
+
+xs <+> ys = zipWith (+) xs ys
+xs <*> ys = sum $ zipWith (*) xs ys
+
+newtype Mat a = Mat {unMat :: [[a]]} deriving Eq
+
+instance Show a => Show (Mat a) where
+  show xm = "Mat " ++ show (unMat xm)
+
+instance Num a => Num (Mat a) where
+  negate xm = Mat $ map (map negate) $ unMat xm
+  xm + ym   = Mat $ zipWith (<+>) (unMat xm) (unMat ym)
+  xm * ym   = Mat [[xs <*> ys | ys <- transpose $ unMat ym] | xs <- unMat xm]
+  fromInteger n = Mat [[fromInteger n]]