> The kinds of bugs that get caught by a static type system are also caught by a good suite of automated tests, where every test is written before the productio

> The kinds of bugs that get caught by a static type system are also caught by a good suite of automated tests, where every test is written before the production code that makes it pass. To make matters worse, one would also have to write tests that cover every possible path through the function to ensure none of them change a value into a shape the rest of the code doesn't expected. This gets very tedious if it has to be done for every function.