That's still a significant portion of the code-base though. In almost every other language you'd have to write tests to accomplish the same thing. It's certai

That's still a significant portion of the code-base though. In almost every other language you'd have to write tests to accomplish the same thing. It's certainly possible to compose functions that return something of the correct type but not the correct value (in fact, that's trivial to do). Those should be easier to spot/debug/test than the errors the type system checks for you.