Question

For Problem Lec.5.3.3: Functions on Lists Part 2 question 12, I don't understand why (length (cons y y)) is 4. For reference y => (1 2 3)

Answer 1

The list is ((1 2 3) 1 2 3), which is 4 items. The first list is only a single item, because it's in car.

Answer 2

Like our friend above says, the first element is a single item.

In Lisp, lists can contain any kind of elements. (Even other lists.) In that list of yours, the first element is a list (with 3 elements), but that list with 3 elements is /the first/ element of the list (cons y y).

Does that clarify?