22.6 Key access: Answer

Answer for "Key access"

The suggested way of answering this is as follows:

key_access(X) :- stay(X,monday,Copenhagen).
key_access(X) :- stay(X,tuesday,Odensee).
key_access(Beth).

We have used a fact to state the fact that Beth had access to the key. We could also have used a rule:

key_access(X) :- eq(X, Beth).

but that wouldn't have been as elegant as just using a fact. It is Prolog's pattern matching which gives us the freedom to use a fact instead of a rule.


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