Kurzes Snippet:

extendedEuclidean :: Int -> Int -> (Int, Int, Int)
extendedEuclidean a b =
  if b == 0 
  then (a, 1, 0) 
  else (d, t, s - (a `div` b) * t)
  where
    (d, s, t) = extendedEuclidean b (a `mod` b)