[ANN] New indexes for DateAndTime and UUID instances

[Chris Muller]

Hi, I have already added a UUID index to be included
in the next major release (real soon now).  I will,
however, plan to add your DateAndTime index.  Thanks!

> Indexing DateAndTimes
> --------------------------
> A DateAndTime instance includes the offset from UTC
> and has nanoSecond precision. It can also store any
> date
> since  24 November -4713.

That is quite amazing.

> Indexing a full DateAndTime would require a LOT of
> bits, which is probably why Chris never added an
> index for
> them.

Ahem.  Actually, I haven't had time to purge my
rudimentary Ma time objects yet.  I *do* plan to do
that when I get time.  Chronology looks fantastic, if
a bit heavyweight on DateAndTime (but now I understand
why, stretching nanosecond precision so far forward
and back).

> Fortunately, we do not need
> 	a) to store dates all the way back to the dawn of
> time
> 	b) nano second precision
> 	c) to store dates infinitely far into the future.
> 
> MaDateAndTimeIndex allows the developer to specify:
> 	a) the start epoch (dates on or before this are not
> allowed)
> 	b) the clock precision (one of 1 second. 1
> milliSecond, 1 nanoSecond)
> 	c) the duration into the furture (ie. epoc +
> duration = last date which is allowed)

And from these three it (hopefully) calculates the
needed keysize for you.  Beautiful!

> The default has a keySize of 72 bits and gives
> nanoSecond precision from 1 January 1900 for 1000
> years!

And this, (hopefully) is achieved simply with
"MaDateAndTimeIndex new".

> Chris, if you like this work, feel free to modify it
> and add it to Magma.

I like it very much.  I will plan to add it.

Thanks!
  Chris