clojure-koans/04_vectors.clj

  ; "You can use vectors in clojure as array-like structures"
  (= 1 (count [42]))

  ; "You can create a vector from a list"
  (= [1] (vec '(1)))

  ; "Or from some elements"
  (= [nil nil] (vector nil nil))

  ; "But you can populate it with any number of elements at once"
  (= [1 2] (vec '(1 2)))

  ; "Conjoining to a vector is different than to a list"
  (= __ (conj [111 222] 333))

  ; "You can get the first element of a vector like so"
  (= :peanut (first [:peanut :butter :and :jelly]))

  ; "And the last in a similar fashion"
  (= :jelly (last [:peanut :butter :and :jelly]))

  ; "Or any index if you wish"
  (= :jelly (nth [:peanut :butter :and :jelly] 3)) ;; J - index #'s still start with 0 in Clojure.

  ; "You can also slice a vector"
  (= [:butter :and] (subvec [:peanut :butter :and :jelly] 1 3)) ;; J - slicing with subvec includes first index arg and excludes second

  ; "Equality with collections is in terms of values"
  (= true (list 1 2 3) (vector 1 2 3)) ;; J - lists and vectors are comparable.