[Oops, replied only to Ashley, not to list.]
> From: Ashley Yakeley [mailto:ashley@semantic.org]
>
> There's something to be said for representing date and time of day
> separately in calendar time, something like this:
>
> data CalendarDate = CalendarDate ...
>
> data TimeOfDay = TimeOfDay ...
>
> data CalendarTime = CalendarTime
> {
> ctDate :: CalendarDate,
> ctTime :: TimeOfDay
> }
>
> On the other hand, it adds two levels of construction to CalendarTime.
I'm not convinced. I think it would be simpler and just as functional to
have just a CalendarTime and a Duration. You would represent a time by a
Duration (i.e. time since midnight), and a day with no time component would
be represented by that date at midnight. You could add a Duration to a
CalendarTime to get a date-with-time.
Durations have other uses (differences between two CalendarTimes, summing
other Durations, etc), whereas a TimeOfDay is limited to a 24hr period.
Alistair.
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