I am trying to create a set of n integers: {0, 1, 2, 3, 4, ..., n}.

What is the most efficient way to do so?

It looks like {for (var i = 0; i < n; i++) i}} is more efficient than List.generate(n, (j) => j).toSet():

On the dartpad:

void main() {
  const size = 1000;
  const n = 1000;
  final startList = DateTime.now();
  for (var i = 0; i < n; i++) {
    final s = List.generate(n, (j) => j).toSet();
  }
  final endList = DateTime.now();
  print('List: ${endList.difference(startList)}');

  final startSet = DateTime.now();
  for (var i = 0; i < n; i++) {
    final s = {for (var i = 0; i < n; i++) i};
  }
  final endSet = DateTime.now();
  print('Set: ${endSet.difference(startSet)}');
}

List: 0:00:00.194000
Set: 0:00:00.104000

But are there other (more efficient) ways?