Type System Safe for C#

Safe.cs

[Fact]
  public void ThisIsSafe()
  {
      int a = 5;
      int b = a + 2; //OK

      bool test = true;

      // Error. Operator '+' cannot be applied to operands of type 'int' and 'bool'.
      int c = a + test;
  }

  [Fact]
  public void ThisIsUnSafe()
  {
      var integers = new ArrayList();
      integers.Add(1);
      integers.Add(2);
      integers.Add("3"); // **PROBLEM**

      for (int i = 0; i < integers.Count; ++i)
      {
          int integer = (int)integers[i];
          // do something
      }
  }
}