const.dart

void main() {
  var a = const ImmutablePoint(1, 1);
  var b = const ImmutablePoint(1, 1);

  var c = ImmutableCircle();
  var d = ImmutableCircle();
  print(identical(a, b));
  print(identical(c, d));
}

class ImmutablePoint {
  static const ImmutablePoint origin = ImmutablePoint(0, 0);

  final double x, y;

  const ImmutablePoint(this.x, this.y);
}

class ImmutableCircle {}