Typing isn't a strong enough tool to combat that class of problem; you can fix the type signatures while introducing a semantic break. You need tests and if you have tests, what does typing bring? Keep your tests fast, measure and maintain a speed of >250 tests per second and remember to test behaviour not implementation - you won't go far wrong.
IDEs have been performing refactoring changes on our behalf in dynamic languages for years at this point. Don't manually edit when we've never had such powerful tooling available to us
* https://www.jetbrains.com/help/pycharm/product-refactoring-tutorial.html
* https://www.jetbrains.com/help/pycharm/structural-search-and-replace.html
Typing has a time and a place, that is without a doubt but the world is better viewed without the static typing lens permanently affixed in place, your efficacy will increase.
I’d never choose to have myself do more work if it’s not needed and the computer can do it.
Those automated refactorings would Not have helped in the situation I mentioned above.
It’s whether it continues to work tomorrow after you’ve added or removed a behaviour. Tests are the secret sauce that keep the cost of change low.
Refactoring (a commit with zero changes to test code) is the other key pillar of long term codebase health.
Pretty simple, it helps when you do a refactoring that changes the type of the value passed somewhere from number to number[] and the compiler instantly tells you that that’s illegal.
I did something similar just the other day when I had a shared config file read by both TS scripts and Python scripts and I needed to change the format to support a new feature. On the ts side I updated the typedef and the compiler pointed out to me every area that needed updating, on the Python side I had to spend a good chunk of time manually going through the script to figure out what needed updating.