Add all the A tasks

Task/Arithmetic-Complex/Haskell/arithmetic-complex-1.hs

@@ -0,0 +1,14 @@
+import Data.Complex
+
+main = do
+  let a = 1.0 :+ 2.0    -- complex number 1+2i
+  let b = 4             -- complex number 4+0i
+  -- 'b' is inferred to be complex because it's used in
+  -- arithmetic with 'a' below.
+  putStrLn $ "Add:      " ++ show (a + b)
+  putStrLn $ "Subtract: " ++ show (a - b)
+  putStrLn $ "Multiply: " ++ show (a * b)
+  putStrLn $ "Divide:   " ++ show (a / b)
+  putStrLn $ "Negate:   " ++ show (-a)
+  putStrLn $ "Inverse:  " ++ show (recip a)
+  putStrLn $ "Conjugate:" ++ show (conjugate a)

Task/Arithmetic-Complex/Haskell/arithmetic-complex-2.hs

@@ -0,0 +1,8 @@
+*Main> main
+Add:      5.0 :+ 2.0
+Subtract: (-3.0) :+ 2.0
+Multiply: 4.0 :+ 8.0
+Divide:   0.25 :+ 0.5
+Negate:   (-1.0) :+ (-2.0)
+Inverse:  0.2 :+ (-0.4)
+Conjugate:1.0 :+ (-2.0)