In Functional Programming, is it considered a bad practice to have incomplete pattern matchings

Question

Is it generally considered a bad practice to use non-exhaustive pattern machings in functional languages like Haskell or F#, which means that the cases specified don\'t cove

Answer 1

I think that it depends quite a bit on the context. Are you trying to write robust, easy to debug code, or are you trying to write something simple and succinct?

If I were working on a long term project with multiple developers, I'd put in the assert to give a more useful error message. I also agree with Pascal's comment that not using a wildcard would be ideal from a software engineering perspective.

If I were working on a smaller scale project on which I was the only developer, I wouldn't think twice about using an incomplete match. If necessary, you can always check the compiler warnings.

I think it also depends a bit on the types you're matching against. Realistically, no extra union cases will be added to the list type, so you don't need to worry about fragile matching. On the other hand, in code that you control and are actively working on, there may well be types which are in flux and have additional union cases added, which means that protecting against fragile matching may be worth it.