title: Is there any data structure in Clojure that allows removing an arbitrary element in O(1) or O(log n)?
body: <p>In code, I'm looking for <code>remove-nth</code> and <code>some-coll</code> that will be O(1) or O(log n) for arbitrarily large collections.</p>
  
  <pre><code>(=
    (remove-nth (some-coll "a" "b" "c" "d") 2)
    (some-coll "a" "b" "d"))
  </code></pre>
  
  <p>I'm preferably looking for a solution that uses only the standard library, but I'd be interested in solutions that use external libraries.</p>