I've got the first 2 stages working in haskell, but the third stage fails with
PatternMatchFail (Main.hs:(12,5)-(21,38): Non-exhaustive patterns in case )
I don't have any non-exhaustive pattern matches or case statements in my code, it seems the
kata is broken for me.

just to explain the task a bit clearer:

this is the number n: 35231

A list with each number as an own entry looks like this:

[3,5,2,3,1]

Now reverse the order of the list like this:

[3,5,2,3,1]

[1,3,2,5,3]

the last number in the list becomes the first, the second-last the second
and so on..