Data.Time questions

Ashley Yakeley ashley at
Sun May 11 21:06:53 EDT 2008

Bjorn Buckwalter wrote:
> Dear all,
> I've implemented 'ParseTime' and 'Read' instances for 'AbsoluteTime'.
> Before submitting a patch I want to confirm with you that they belong
> in 'Data.Time.Format.Parse' as opposed to 'Data.Time.Clock.TAI'. Is
> this correct?

I'm not sure if it matters, since it is instances rather than new 
exported symbols, and anyone using those instances must have both 
AbsoluteTime and ParseTime in scope already.

> I'm doing work on additional time coordinates of interest to e.g.
> astrodynamicists. In particular Terrestrial Time (TT = TAI + 32.184
> seconds, previously known as Terrestrial Dynamical Time or TDT) and
> perhaps Geocentric Coordinate Time (TCG) and others. Would you be
> interested in receiving patches with these rather esoteric time
> coordinates? If not I'll release them in a new "time-astro" package.

Are you going to create a new type for TT?

TT is isomorphic to TAI in the category of measurements. I've generally 
tried to avoid separate types for isomorphic measurements. That's why 
it's called AbsoluteTime rather than TAITime...

Ashley Yakeley

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