A small British firm shows that software bugs aren't inevitable (2005)(spectrum.ieee.org)

    def sum(a, b) when is_integer(a) and is_integer(b) do
      a + b
    end

    def sum(a, b) when is_list(a) and is_list(b) do
      a ++ b
    end

    def sum(a, b) when is_binary(a) and is_binary(b) do
      a <> b
    end

    sum 1, 2
    #=> 3

    sum [1], [2]
    #=> [1,2]

    sum "a", "b"
    #=> "ab"

    spouseDOB :: User -> Maybe DateOfBirth
    spouseDOB u = case getSpouse u in
                    s -> getDOB s
                    Nothing -> Nothing

    DateOfBirth* spouseDOB(User& user) {
      Spouse* spouse = getSpouse(user);
      if (spouse)
        return &spouse->dateOfBirth;
      return NULL;
    }

    int **