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396000 (2) [Avatar] Offline
The solution for 17.2 exercise (page 575) doesn't obey left identity and right identity laws. If we would try to mappend some events or probs with mempty we will get mempty instead of the events or probs. It seems cartCombine function from page 198 (listing 17.13) incorrectly handle empty lists.
iLico (1) [Avatar] Offline

does only substituting with the solution from page 575 will work?
I understand the refactoring process should also edit the corect calling of the data contructor in the function usinf the data types.
I didn't manage to make it work.
does their exist a complete refactored version for Q17.2?