(require '[clojure.string :as str])

;; Empty string literal
(def some-empty-string "")
;; Built out of nothing
(def another-empty-string (str))

(when (empty? some-empty-string)
  (println "some string is empty"))

(when (empty? another-empty-string)
  (println "another string is empty"))

;; blank? is true for nil and for spaces too
(when (str/blank? "   ")
  (println "a string of spaces is blank"))