TimeRFC822 - Cookbook - s c h e m a t i c s : c o o k b o o k

Writing and Parsing RFC 822 Dates and Times

Problem

You need to convert from struct:time to RFC 822 format Dates and Times.

Solution

mzlib provides one solution:

> (require (lib "date.ss"))
> (date-display-format 'rfc2822)
> (date->string (seconds->date (current-seconds)) #t)
"Wed, 28 Apr 2004 10:37:20 -0600"

However, many applications that use RFC 822 require all output in GMT. mzlib's seconds->date assumes the current timezone, but SRFI 19 allows you to specify a time zone in the 2nd argument to seconds->date-utc.

> (require (lib "time.ss" "srfi" "19"))
> (date->string (time-utc->date (current-time) ) "~a, ~d ~b ~Y ~T ~z" )
"Wed, 28 Apr 2004 11:21:53 -0600"
> (date->string (time-utc->date (current-time) 0) "~a, ~d ~b ~Y ~T ~z" )
"Wed, 28 Apr 2004 17:22:10 Z"

If you need to parse dates as input, you can use string->date from SRFI 19:

> (string->date "Wed, 28 Apr 2004 17:22:10 Z" "~a, ~d ~b ~Y ~H:~M:~S ~z" )
#<struct:date>

Discussion

RFC 822 is used frequently as the basis for exchanging dates and times, particularly in Internet applications. You should also be aware that the struct:date provided by mzlib is not compatible with SRFI 19's struct:date, so you should pick one and stick with it, to avoid mixing types. Also, it should be noted that the ~a and ~b format specifiers are locale sensitive, so if you're not running with an English locale, the output may be incorrect.

References

RFC-822 - Standard for the format of ARPA Internet text messages

RFC-1123 - Requirements for Internet Hosts - Application and Support

Contributors

-- GordonWeakliem - 28 Apr 2004

CookbookForm
TopicType:	Recipe
ParentTopic:	TimeRecipes
TopicOrder:	050

Current Rev: r1.3 - 15 Oct 2007 - 11:58 GMT - JeromeBaum, Revision History:Diffs | r1.3 | > | r1.2 | > | r1.1

Copyright © 2004 by the contributing authors. All material on the Schematics Cookbook web site is the property of the contributing authors.
The copyright for certain compilations of material taken from this website is held by the SchematicsEditorsGroup - see ContributorAgreement & LGPL.
Other than such compilations, this material can be redistributed and/or modified under the terms of the GNU Lesser General Public License (LGPL), version 2.1, as published by the Free Software Foundation.
Ideas, requests, problems regarding Schematics Cookbook? Send feedback. / You are Main.guest

PLT Scheme	SISC
Scheme48	SCM
MIT Scheme	scsh
JScheme	Kawa
Chicken	Guile
Bigloo	Tiny
Gambit	LispMe
Gauche	Chez