Nothing wrong with this, but you could just remove the return keyword and the ; symbol.

Ah yes, I had a sinking feeling last night I may have inadvertantly asked you to solve the halting problem there so apologies for that!

I'm glad it helped. I will see what I can do (at least a hint in the description).

edit: Sadly I can't test dropS as it will traverse an infinite spine. Therefore I would have to test with a timeout. I'm not sure whether that's possible.

Thank you so much for your suggestions - it was dropS not handling negatives that was the killer. Is it possible to add a failing test for this?
I will have another attempt at getting pure stream based fibS and primeS. Thanks again :)

Things that I noticed:

• dropS: not working for negative numbers
• fibS: That's not how you should solve it (without lists please). (Hint: Think about a recursive definition of fibonacci numbers by using the stream itself.)
• primeS: I can't see what's the issue here, but again don't use lists please. Look up how a prime sieve algorithm works and implement it using streams. (It's very short, I promise and even bad ones should work.)
• Other that that it might also be related to codewars. Are you blocking JavaScript?

I have even tried https://hackage.haskell.org/package/primes-0.2.1.0/docs/Data-Numbers-Primes.html and it still times out.
Again, the sample tests work fine. I'm running out of ideas, checking my Fibonacci solution.

Really struggling to pass the final tests - I suspect my primeS is too inefficient.
Can anyone offer any hints? I've tried to translate lazy list based approaches to streams but nothing seems fast enough to pass the tests.

Nothing

Is "the minimum number of letters you have to add, remove or replace in order to get from the entered word to one of the dictionary" not the definition of the distance algorithm required? Or is it not that precise?

I found this very challenging, and honestly I'm still quite mystified by Monads but this has been a little confidence boost and a step further to a deeper understanding of the topic.