Sequence abstraction

Fixme work in progress

  1. (first '(1 2 3 4 5))
  2. (rest '(1 2 3 4 5))
  3. (last '(1 2 3 4 5))
  1. (defn nth [items n]
  2.  (if (= n 0)
  3.    (first items)
  4.    (recur (rest items) (- n 1))))
  6. (define squares '(0 1 4 9 16 25))
  8. (nth squares 3)