> I'd be very surprised if there weren't similar issues in these languages, since these are all duck-typed and the topic at hand is "bugs prevented by rigorous

> I'd be very surprised if there weren't similar issues in these languages, since these are all duck-typed and the topic at hand is "bugs prevented by rigorous up-front type checking." Duck typing means that I can run an incomplete program, that is, one that will misbehave for certain inputs. It turns out that running incomplete programs is incredibly useful. Yes, I can spend time up front to fake a complete program and remove the fakeness as I provide additional completeness, but ....