Proposal for custom time string formatting in std.datetime

[Kagamin]

On Wednesday, 28 December 2011 at 00:15:00 UTC, Jonathan M Davis 
wrote:
> By having SysTime, you don't need extra time types.

Hmm... if you don't have extra time types, how do you format a 
SysTime? To convert a SysTime to a string you usually need year, 
month and day. Calculating a year takes some time: leap years, 
possibly time zone adjustment; when you need month, you have to 
recalculate year, since SysTime doesn't hold it. That's how it 
works?