Finally fixed in 2022.

Not the tests, I don't understand them anyway, but the description: pointing to an external document that points to external documents that perhaps explain what to do does not really help. The description itself is the place to explain what needs to be done.

As it is, there are just too few clues if you don't already know what to do.

I'm still hoping for the kata or the tutorial that makes me understand monads. I haven't found one yet, and this isn't it either. And I think it could have been.

This seems like it should be clarified in the description.

I think it's way too easy. Just playing type tetris / cat-programming ("if it fits, it sits") can be used to solve it in a couple minutes without actually having to think about it.

I really enjoyed working through this. Thanks!

I thought the concepts and the paper were interesting, but the actual coding was on the easy side. It was too easy to just copy and paste with a little light editting from the paper. But, users think it's 3kyu, so who am I to argue :) I did enjoy it.

Each move is a swap of the two positions, so the order of the tuple doesn't matter. The second move swaps positions 1 and 2. Since the ball is in position 1 at this point (because of the first move), the ball moves to position 2.

How come the second swap moves it from 1 to 2 when it is said that the first one in the tuple is FROM and second one is TO? I really think there is a typo in this test . Thanks for the explanation.

i corrected that nil test case with zero, will add some more test cases soon. I didn't get what you said in last of your solution. I would appriciate a more descriptive form of it. Thnkx

I found it kind-of tricky, but only because I had trouble coming up with an intuition for the type of foldExpr. Once I got past that mental barrier, it was quite simple, but so interesting that I definitely think it was worthwhile. Thanks for sharing this functional pearl with us on here!

The ramdom tests where meamt to be hiddem, amd now you've exposed them! :(

Fixed.

Shouldn't that be a suggestion, not an issue?

I really love to see that technique in action and it was really fun. At some points I needed time to figure out the types, so I think difficulty wise it was pretty reasonable.

I just retried and sadly there seems to be no way to keep most of this from the user (as the Preload just don't work) - maybe you can help me out here? For now I'll close this