subs-to.clj

(defn subs-to
  "Like subs, but does not throw if index is out of range"
  ([s start]
     (subs-to s start (count s)))
  ([s start end]
     (if (or (<= (count s) start) (<= end start))
       ""
       (subs s start (min (count s) end)))))


(deftest subs-to
  (let [s "Clojure"]
    (is-= "o" (string/subs-to s 2 3))
    (is-= "lo" (string/subs-to s 1 3))
    (is-= "lojure" (string/subs-to s 1)))
  (let [s "abcd"]
    (is-= "" (string/subs-to s 100))
    (is-= "" (string/subs-to s 100 200))
    (is-= "cd" (string/subs-to s 2 100))))