2016 Update

Task/Fibonacci-sequence/Haskell/fibonacci-sequence-5.hs

@@ -1,3 +1,4 @@
-fib 0 = 0 -- this line is necessary because "something ^ 0" returns "fromInteger 1", which unfortunately
-          -- in our case is not our multiplicative identity (the identity matrix) but just a 1x1 matrix of 1
-fib n = last $ head $ unMat $ (Mat [[1,1],[1,0]]) ^ n
+fib n = go n 0 1
+    where
+    go n a b | n==0 = a
+             | otherwise = go (n-1) b (a+b)