On Mon, Feb 22, 2010 at 4:49 PM, Buddha Buck <blaisepas...@gmail.com> wrote: > On Mon, Feb 22, 2010 at 4:38 PM, Daniel Ruoso <dan...@ruoso.com> wrote: >> The biggest difference proposed by the use of TAI is that when you ask >> for the number of seconds between "2008-12-31T23:59:59+0000" and >> "2009-01-01T00:00:00+0000" you'll get 2 because of the leap second. But >> you don't need to know how many seconds there were in the TAI scale >> since the 1958 epoch to find that out, you just need to know when we had >> leap seconds. > > What do you mean? The number of seconds between > 2008-12-31T23:59:59+0000 TAI and 2009-01-01T00:00:00+0000 TAI was 1 > because TAI doesn't have leap seconds. UTC does, but TAI doesn't.
Exactly. If Perl6 is thoroughly TAI, then any time you ask it what time it is you'll get an answer that's 34 or more seconds fast compared to the clock on the wall. In exchange for this, you know that you can take the number of minutes, hours, or days between two times and multiply by a constant to get an accurate count of seconds between them. If, instead, Perl6 uses UTC, then its time labels will agree with our clocks. But that means that some minutes, hours, and days will be a second longer than the rest, so you can no longer do a simple multiplication to convert to seconds. (Unless you're looking for a POSIX time stamp instead of the actual length of the interval.) I submit that if the inputs and outputs of Temporal are UTC, then Perl is using UTC, not TAI. Is it TAI internally? Well if it's manipulating years, months, days, hours, and minutes as their TAI values, then yes, but if it's just working with an absolute count of atomic seconds, then there's no reason to say that it's TAI vs. UTC, because at that level, they completely agree with each other. -- Mark J. Reed <markjr...@gmail.com>
