Support predicates for dealing with date/time representations.
Prolog uses multiple representations for date/time values. This
module converts all these representations into one that is consistent
with the XSD 7-property model.
Prolog uses the following date/time representations, indicated with
We use the following date/time representation, indicated with
The SWI standard library `sgml' uses the following date/time
representation, indicated with `XsdDateTime':
The purpose of this module is to allow the programmer to write all
predicates that use date/time representations to only work with dt/7.
This is a huge date/time-saver!
- cpu_time(:Goal_0, -Delta:double) is det
- date_time_to_dt(+SwiDateTime:compound, -RdfDateTime:compound) is det
- Converts the three Prolog date/time representations to the one
XSD-inspired 7-property model representation (type
Prolog uses the following three date/time representations (type
Apart from a difference in compound structure there are also two
differences in value semantics:
- In Prolog S represents the seconds as a floating point
number between 0.0 and 60.0. In XSD S represents the
seconds as a decimal number greater than or equal to 0 and
less than 60.
- In Prolog Off represents the offset relative to UTC in
seconds as an integer, where positive values are west of
Greenwich. In XSD Off represents the offset relative to UTC
in minutes as an integer between -840 and 840 inclusive.
- dt_to_date_time(+RdfDateTime:compound, -SwiDateTime:compound) is det
- Conversion from the XSD-inspired 7-property model to the three
Prolog date/time compound term representations.
- dt_to_timestamp(+RdfDateTime:compound, -Timestamp:float) is det
- is_dt(@Term) is semidet
- is_date_time(@Term) is semidet
- timestamp_to_dt(+Timestamp:float, -RdfDateTime:compound) is det
- date_time_masks(+Masks:list(atom), +SwiDateTime1:compound, -SwiDateTime2:compound) is det
- Apply an arbitrary number of date/time masks.
- See also
- - date_time_mask/3
- now(-RdfDateTime:compound) is det
- Return the current date/time as a
dt-typed compound term.
- number_of_days_in_month_of_year(?Year:integer, ?Month:between(1,12), ?MaxDay:between(28,31)) is nondet
- The number of days in month of year is:
- 31 if month is 1, 3, 5, 7, 8, 10, or 12;
- 30 if month is 4, 6, 9, or 11;
- 29 if month is 2 and year is a number divisible by 400, or if
year is a number divisible by 4 but not by 100;
- 28 otherwise.
- date_time_label(+SwiDateTime:compound, -Label:string) is det
- date_time_label(+SwiDateTime:compound, -Label:string, +Options:options) is det
- dt_label(+RdfDateTime:compound, -Label:string) is det
- dt_label(+RdfDateTime:compound, -Label:string, +Options:options) is det
- generate_as_digits(+N:nonneg, +NumberOfDigits:nonneg)// is det
- generate_as_digits(+N:nonneg, +Base:positive_integer, +NumberOfDigits:nonneg)// is det
- Generate the non-negative integer N using exactly NumberOfDigits
digits, using `0' as padding if needed.
The following predicates are exported, but not or incorrectly documented.
- date_time_label(Arg1, Arg2, Arg3)
- dt_label(Arg1, Arg2, Arg3)
- generate_as_digits(Arg1, Arg2, Arg3, Arg4, Arg5)