You’re assuming I would endorse this as a good approach in Python in the real world.
I was merely trying to show how to quickly emulate the Haskell example with less code in Python. Both the Haskell approach and asserting on types in Python seem like wastes of time to me personally, and I’d rather just have copyFile by itself and consenting adults can pass the args they want to pass. Use unit tests to make sure you’re not passing paths the wrong way.
Also, what’s with the attitude? “You know how to complicate something very simple” (from ~15 lines of Python?) — geez, you must be a joy to work with.
It addresses exactly the cases you care about, whereas trying to bake it into designs or type system usually adds heavy restrictions that don’t necessarily have anything to do with your exact use cases.
Basically from a You Aren’t Gonna Need It point of view, doing it in tests lets you minimally address the real use case with much less risk of premature or incorrect abstraction.
In my experience, premature abstraction is one of the worst problems in business software. To contrast two far ends of the spectrum, minimalistic patchworks of gross hacking are asymmetrically way better than overhead of premature or incorrect abstractions.
What is the advantage here? As I would prefer to have the authors original problem than this.