RFC: Time Library 0.2
ashley at semantic.org
Mon Oct 31 02:04:12 EST 2005
Just in time for HCAR...
Please take a look at my second attempt at writing a replacement for the
standard time library.
Take a look at the Haddock documentation:
Download the source:
Or keep up-to-date:
darcs get http://semantic.org/TimeLib/TimeLib/
It needs GHC 6.4.1. (I haven't tested with 6.4.) Just run "make" to
build the library, tests and documentation. There's also a cabal file
(as a completely separate build process), but I've been having trouble
with that on Mac OS X.
I'm particularly interested in comments from people who try to write
little applications for it. What did you have trouble with? What made no
sense? Also have a look at some use-cases, which get compiled as part of
the package tests:
Major changes since 0.1:
* Moved to Data.Time, since the actual "System" part (getting the
current time and time-zone) is relatively small.
* Big simplification of types. Now tuples are used for calendar data
(such as (year,month,day) for the Gregorian calendar), and the confusing
DayEncoding class has been dropped.
1. There is no leap second table provided, though there is a type
(LeapSecondTable) for such things. Any software compiled with a fixed
table would soon become out of date.
2. There is no table of time-zones provided, since these also change.
However, if there's a good way of getting this from the TZ database on
the machine, I'll add that.
It is actually possible to get the local time-zone for any given time,
indeed one of the test programs finds your local summertime transitions.
The Timezone type includes name, minutes of offset, and a "summertime"
3. The TimeLocale type comes from the already existing System.Locale.
4. It's not possible to expunge POSIX time. Why? Because it's the only
way to do sensible arithmetic on UTC times without knowing the leap
second table and without worrying about one-second offsets.
5. I include Data.Fixed which provides a fixed-point arithmetic type
(wrapper around Integer). It probably should be in a separate package.
It allows dealing with seconds as a single thing, rather than as an
6. I don't have any text-parsing functionality for times. This is a fair
amount of work, so it would be good to know sensible requirements.
7. Time as measured by the CPU since system startup remains in
System.CPUTime, which TimeLib does not intend to replace.
Ashley Yakeley, Seattle WA
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