Why are commands executing out of order?

[Andrea Fontana]

On Saturday, 2 February 2013 at 15:39:00 UTC, Namespace wrote:
>> I've never come across Appenders before. Could you please 
>> explain them a little bit, and what each call in your modified 
>> code does?
>>
>> Thanks,
>>
>> Josh
>
> http://dlang.org/phobos/std_array.html#.Appender
> And read Era's post.

Why Appender has no ~ operator itself?

auto app = appender!string();
app.put("a");  // why not app ~= "a"?