You're meant to check if the string starts with a greeting, not if it contains one.. I thought that was what was intended?

Very nice Kata, Haskell translation kumited

Well, your solution is better where it matters while being just as clean as mine. There's no arguing against that

Well, apart from the O(n) vs O(1) issue, the code is short, clean and easy to understand.

What does the 'Must be able to store values' message mean?

Would really be great if you explained what the context should be... Or at least where to learn what the context is.
I couldn't find anything on Google myself.

OOhhh, it's bill-based? Not money-based?

else:
    pass

^ Why is that even there?

Shouldn't [25, 50, 50] be "YES"?

First customer:
| Customer: €25
| Change: €0
| Register: €0
| Result [Register]: €25
Second Customer:
| Customer: €50
| Change: €25
| Register: €25
| Result [Register]: €25
Third Customer:
| See second customer

...Right?

1. I forgot about that
2. IMO how I do it is prettier; But, thinking about it: Isn't my way less efficient...? (With all the assignments)

This... This works. How?