Bug in Time module
Hi, I discovered a bug in the Time module. If I run the following code snippet: main :: IO () main = do t0 - getClockTime system sleep 120 t1 - getClockTime print (t1 `diffClockTimes` t0) The TimeDiff value has a tdSec field greater than 59, and a tdMin field of 0. I guess this is a bug. I am running ghc-5.00.2 on Linux. /Koen. -- Koen Claessen http://www.cs.chalmers.se/~koen phone:+46-31-772 5424 mailto:[EMAIL PROTECTED] - Chalmers University of Technology, Gothenburg, Sweden ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: Bug in Time module
On Wed, Sep 26, 2001 at 16:21:09 +0200, Koen Claessen wrote:
I discovered a bug in the Time module. If I run the
following code snippet:
Just one? ;)
[...]
The TimeDiff value has a tdSec field greater than 59, and a
tdMin field of 0. I guess this is a bug.
I am running ghc-5.00.2 on Linux.
Well, it's consistent with the comments in the code...
From ghc/lib/std/Time.hsc:
[...]
diffClockTimes :: ClockTime - ClockTime - TimeDiff
-- diffClockTimes is meant to be the dual to `addToClockTime'.
-- If you want to have the TimeDiff properly splitted, use
-- `normalizeTimeDiff' on this function's result
--
-- CAVEAT: see comment of normalizeTimeDiff
diffClockTimes (TOD sa pa) (TOD sb pb) =
noTimeDiff{ tdSec = fromIntegral (sa - sb)
-- FIXME: can handle just 68 years...
, tdPicosec = pa - pb
}
normalizeTimeDiff :: TimeDiff - TimeDiff
-- FIXME: handle psecs properly
-- FIXME: ?should be called by formatTimeDiff automagically?
--
-- when applied to something coming out of `diffClockTimes', you loose
-- the duality to `addToClockTime', since a year does not always have
-- 365 days, etc.
--
-- apply this function as late as possible to prevent those rounding
-- errors
normalizeTimeDiff td =
[...]
The behaviour is arguable, but the Time module badly needs a rewrite,
anyway... there are still quite some more problems lurking in there...
Cheers,
Michael
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RE: Bug in Time module
I discovered a bug in the Time module. If I run the following code snippet: main :: IO () main = do t0 - getClockTime system sleep 120 t1 - getClockTime print (t1 `diffClockTimes` t0) The TimeDiff value has a tdSec field greater than 59, and a tdMin field of 0. I guess this is a bug. I'm not sure it's a bug - Haskell 98 doesn't require that the TimeDiff value returned from diffClockTimes is normalised in any way, and it can't be done in general of course because months and years have different numbers of days, even minutes have different numbers of seconds if leap seconds are taken into account. In GHC there's an extension Time.normalizeTimeDiff which does the obvious normalization (but in fact it assumes all months have 30 days, so it looks pretty bogus to me). Cheers, Simon ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: Bug in Time module
| I'm not sure it's a bug - Haskell 98 doesn't require | that the TimeDiff value returned from diffClockTimes | is normalised in any way, and it can't be done in | general of course because months and years have | different numbers of days, even minutes have different | numbers of seconds if leap seconds are taken into | account. You are absolutely right of course. Shouldn't this be regarded as a bug in the Haskell'98 spec then? It is not sure to me at all what a value of TimeDiff really means. Maybe TimeDiff should only contain the fields: tdDay, tdHour, tdMin, tdSec, and tdPicosec? /Koen. ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
