Comment by BoppreH

Yes, with the caveat that I'm assuming generics here. I'm working on a language where you can have:

  def add(a, b):
    return a + b

  add(1, 2) # Works
  add('a', 'b') # Works
  add(1, 'b') # Type error!

So changing one line should never break things outside its "light cone" (call stack + reachable data structures).