(
  var mergeSort = { |arr|

    var merge = {|head, tail|
      var i = 0;
      var j = 0;
      var k = head.size + tail.size;
      head = head.add(0xfffffff);
      tail = tail.add(0xffffff);
      k.collect({
        var h = head[i];
        var t = tail[j];
        if ( h > t ) {
          j = j + 1;
          t;
        } {
          i = i + 1;
          h;
        };
      });
    };

    var mergeSortInternal = { |arr|
      if (arr.size > 1, {
        var q = (arr.size/2).asInt;
        arr = merge.(mergeSortInternal.(arr[0..(q-1)]), mergeSortInternal.(arr[q..]));
      });
      arr;
    };
    
    mergeSortInternal.(arr)
  };

  var start, end;
  var unsorted = (0..2000).scramble;
  
  // run mergeSort vs sort for same scrambled array
  start = Main.elapsedTime;
  mergeSort.(unsorted);
  end = Main.elapsedTime;
  ("mergeSort: " ++ ((end-start)*1000) ++ "ms").postln;
  
  start = Main.elapsedTime;
  unsorted.sort();
  end = Main.elapsedTime;
  ("sort: " ++ ((end-start)*1000) ++ "ms").postln;
)