I am trying to parse various date and time formats using the

function found in (GHC 6.6.1) Data.Time.Format. The one that is giving me trouble looks like this:

2008-06-26T11:00:00.000-07:00

Specifically, the time zone offset isn't covered by the format

dons's blog entry on parsing dates might point somewhere useful http://cgi.cse.unsw.edu.au/~dons/blog/2006/11/12#rpn-reloaded t. Don Stewart Sent by: haskell-cafe-bounces@haskell.org 10/15/2007 08:25 PM To Justin Bailey cc Haskell-Cafe Subject Re: [Haskell-cafe] Help parsing dates and times jgbailey: parseTime parameters

given. I can almost parse it with this:

%FT%X.000

But that doesn't take into account the "-07:00" bit. I'm sure this has been solved - can someone point me to the solution? Thanks in advance.

Is there anything in the parsedate library? http://hackage.haskell.org/cgi-bin/hackage-scripts/package/parsedate-2006.11... http://hackage.haskell.org/packages/archive/parsedate/2006.11.10/doc/html/Sy... -- Don _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.

On Oct 16, 2007, at 16:16 , Bjorn Bringert wrote:

On Oct 16, 2007, at 2:25 , Don Stewart wrote:

...

jgbailey:

...

I am trying to parse various date and time formats using the parseTime function found in (GHC 6.6.1) Data.Time.Format. The one that is giving me trouble looks like this:

2008-06-26T11:00:00.000-07:00

Specifically, the time zone offset isn't covered by the format parameters given. I can almost parse it with this:

%FT%X.000

But that doesn't take into account the "-07:00" bit. I'm sure this has been solved - can someone point me to the solution? Thanks in advance.

Try %z

(see http://www.haskell.org/ghc/docs/latest/html/libraries/time/ Data-Time-Format.html#v%3AformatTime for all the format specifiers).

...

Is there anything in the parsedate library?

http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ parsedate-2006.11.10 http://hackage.haskell.org/packages/archive/parsedate/ 2006.11.10/doc/html/System-Time-Parse.html

-- Don

parsedate is obsolete, unless you have ghc < 6.6.1. It was rewritten to become what is now the date parsing code in the time package.

Hmm, perhaps I should clarify this: parsedate and time-1.1.1 (which comes with GHC 6.6.1) have different APIs. parsedate produces CalendarTimes, and the code in time-1.1.1 produces the new time and date data types. So I guess parsedate isn't actually obsolete, rather, it's for use with the package currently known as 'old-time'. /Björn

On Oct 16, 2007, at 17:54 , Justin Bailey wrote:

On 10/16/07, Bjorn Bringert wrote:

Hmm, perhaps I should clarify this: parsedate and time-1.1.1 (which comes with GHC 6.6.1) have different APIs. parsedate produces CalendarTimes, and the code in time-1.1.1 produces the new time and date data types. So I guess parsedate isn't actually obsolete, rather, it's for use with the package currently known as 'old-time'.

Given this date string:

2008-06-26T11:00:00.000-07:00

The problem is the parseTime function in Data.Time.Format is a little too strict. The following GHCi session shows the different behaviors. Notice how %Z is unable to parse the time zone offset in any case. First we try parseTime:

...

:m + Data.Time System.Time.Parse System.Locale let dateStr = "2008-06-26T11:00:00.000-07:00" parseTime defaultTimeLocale "%FT%X.000%z" dateStr :: Maybe UTCTime Nothing parseTime defaultTimeLocale "%FT%X.000-%z" dateStr :: Maybe UTCTime Nothing parseTime defaultTimeLocale "%FT%X.000" dateStr :: Maybe UTCTime Nothing

I guess you really want a ZonedTime here, if you want to retain the time zone info. It seems like %z and %Z require 4 digits for a time zone offset, without a colon. This works:

parseTime defaultTimeLocale "%FT%X.000%z" "2008-06-26T11:00:00.000-0700" :: Maybe ZonedTime Just 2008-06-26 11:00:00 -0700

Should we just add XX:XX as an alternative time zone offset format accepted by %z and %Z? Is this a standard format?

Now parseCalendarTime from the parseDate package:

...

parseCalendarTime defaultTimeLocale "%Y-%m-%dT%H:%M:%S" dateStr Just (CalendarTime {ctYear = 2008, ctMonth = June, ctDay = 26, ctHour = 11, ctMin = 0, ctSec = 0, ctPicosec = 0, ctWDay = Thursday, ctYDay = 1, ctTZName = "UTC", ctTZ = 0, ctIsDST = False}) parseCalendarTime defaultTimeLocale "%Y-%m-%dT%H:%M:%S.000%Z" dateStr Nothing

Hmm, ok, parsedate allows garbage at the end. I wonder what is the right thing to do here. /Björn

On Tue, 2007-10-16 at 09:25 -0700, Justin Bailey wrote:

On 10/16/07, Bjorn Bringert wrote:

Should we just add XX:XX as an alternative time zone offset format accepted by %z and %Z? Is this a standard format?

Yes, this is standard; see below.

I'm not sure, but I am getting this date from Google in their XML feeds representing calendar data. The specific element is "gd:when", documented here:

http://code.google.com/apis/gdata/elements.html#gdWhen

That refers to XML Schema; the dateTime type in XML Schema is standardized here: http://www.w3.org/TR/xmlschema-2/#dateTime (and time zone offsets are required to have a colon in this format). Carl Witty