alt Hacker NewsOr: I’m not going to do this refactor at all, even though it would improve the codebase, because it will be near impossible to ensure everything is correct after making so many changes.
To me, this has been one of the biggest advantages of both tests and types. They provide confidence to make changes without needing to be scared of unintended breakages.
There's a tradeoff point somewhere where it makes sense to go with one or another. You can write a lot of codes in bash and Elisp without having to care about the type of whatever you're manipulating. Because you're handling one type and encoding the actual values in a typesytem would be very cumbersome. But then there are other domain which are fairly known, so the investment in encoding it in a type system does pay off.