diff options
-rw-r--r-- | doc/ref/srfi-modules.texi | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/doc/ref/srfi-modules.texi b/doc/ref/srfi-modules.texi index 95509b278..3d4415629 100644 --- a/doc/ref/srfi-modules.texi +++ b/doc/ref/srfi-modules.texi @@ -2383,17 +2383,6 @@ functions and variables described here are provided by (use-modules (srfi srfi-19)) @end example -@strong{Caution}: The current code in this module incorrectly extends -the Gregorian calendar leap year rule back prior to the introduction -of those reforms in 1582 (or the appropriate year in various -countries). The Julian calendar was used prior to 1582, and there -were 10 days skipped for the reform, but the code doesn't implement -that. - -This will be fixed some time. Until then calculations for 1583 -onwards are correct, but prior to that any day/month/year and day of -the week calculations are wrong. - @menu * SRFI-19 Introduction:: * SRFI-19 Time:: @@ -2593,6 +2582,16 @@ The fields are year, month, day, hour, minute, second, nanoseconds and timezone. A date object is immutable, its fields can be read but they cannot be modified once the object is created. +Historically, the Gregorian calendar was only used from the latter part +of the year 1582 onwards, and not until even later in many countries. +Prior to that most countries used the Julian calendar. SRFI-19 does +not deal with the Julian calendar at all, and so does not reflect this +historical calendar reform. Instead it projects the Gregorian calendar +back proleptically as far as necessary. When dealing with historical +data, especially prior to the British Empire's adoption of the Gregorian +calendar in 1752, one should be mindful of which calendar is used in +each context, and apply non-SRFI-19 facilities to convert where necessary. + @defun date? obj Return @code{#t} if @var{obj} is a date object, or @code{#f} if not. @end defun |