Double List in Logic
This problem uses the Logic starter file located here.
Write facts to define
double-length. You may use anything already included in the starter file as well as other facts defined in previous questions.
double-length releates two lists with the second list being a copy of the first list with every element repeated twice.
(fact (double-list ; YOUR CODE HERE )) (query (double-list (1 2 3) (1 1 2 2 3 3))) ; expect Success! (query (double-list (1 2) ?what)) ; expect Success! ; what: (1 1 2 2)
(fact (double-list () ())) (fact (double-list (?first . ?rest) (?first ?first . ?new-rest)) (double-list ?rest ?new-rest))
In our base fact, we note that the
double-list of the empty list is just the empty list. In our recursive case, we focus on breaking up our first list into
rest, then we note that the second list is just the same as the original with an extra item,
first added in the middle.
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