@aerotune @travelerspb I see what you mean. I appreciate that not mutating the original string is better, I added a new solution here: http://www.codewars.com/kata/reviews/55f20b5169b42aa91b0000dc/groups/5b1ccdb7777ab7180e000130
What I strive for is to go the 'confident ruby' way of narrative code, where managing the input is clearly distinguished from the work performed on that input.
Thanks for your comments!

Nice! I always forget about Set...

Like!

Nice!!

Like it, very neat :thumbs_up:

The instructions suggest that it must be checked case-insentive.
I added a test to test that, it didn't pass. But it did pass the submit - tests. For 8th kyu, I'd leave the caseinsensitivity out. For higher kyu's adjust the tests?

In Ruby, I'd score this 8kyu instead of 7

Love it!

This is an easy kata, much easier than most 8th kyu. I'd make this an 8th kyu as well.

In Ruby, I would not score this a 7 kyu kata, but an 8.

You are right. I mean of course: changing this one FROM 7 to 8 kyu

This kata is easier than most 8 kyu kata's (at least in Ruby). How about changing to 7 kyu?

How about adding the 'date and time' tag?

Love it!

The tests provided in the ruby kata are misspelled: they call count_positives_sumNegatives, the tests itself call :count_positives_sum_negatives