Note: It looks clever, but can fail when input has more than a one correct answer (yeah, real life data ;)

@coreyoconnor please use spoiler flag next time.

Well, the ones that have been updated might not work with the old version, so on most, it will probably be disabled.

so it means in every haskell kata we can still select either versions, right? thanks for explaining :)

Its because some katas haven't been updated yet, so the version hasn't been removed yet. It will be removed eventually.

oh, okay. but it makes me wonder why we have the GHC 7 option listed though...

Make sure you have GHC 8.2 selected.

can compile using the test button, but when clicked "Attempt", following message showed up:

Kata/AdditionCommutesSpec.hs:12:8:
    Could not find module `Test.Hspec.Codewars'
    Perhaps you meant
      Test.Hspec.Compat
      Test.Hspec.Core (from hspec-2.2.4@hspec_GEAgkH1Gbr9BY0qzvd784f)
      Test.Hspec.Core.Tree
    Use -v to see a list of the files searched for.