WCC 2012.25 + 2012.26

Main.hs

import Data.Bits

mySum :: Int -> Int -> Int
mySum a b
  |carry == 0 = result
  |otherwise = mySum result $ shift carry 1
  where carry  = (.&.) a b
        result = xor a b

mySubtraction :: Int -> Int -> Int
mySubtraction a b = mySum a $ mySum 1 $ complement b

main = do
  print $ mySum 1 2
  print $ mySum 15 50
  print $ mySum 100 100
  print $ mySum 100 (- 100)
  print $ mySubtraction 100 100
  print $ mySubtraction 100 (- 100)