Time Formatting Parsing in Prolog

% Prolog supports date and time handling through various libraries.
% In this example, we'll use the 'library(time)' for time operations.

:- use_module(library(time)).

main :-
    % Get the current time
    get_time(T),
    
    % Format the time according to RFC3339
    format_time(string(FormattedTime), '%FT%T%z', T),
    writeln(FormattedTime),

    % Parse a time string
    parse_time('2012-11-01T22:08:41+00:00', iso_8601, ParsedTime),
    write_term(ParsedTime, []),
    nl,

    % Custom time formatting
    format_time(string(CustomTime1), '%I:%M%p', T),
    writeln(CustomTime1),
    
    format_time(string(CustomTime2), '%a %b %d %H:%M:%S %Y', T),
    writeln(CustomTime2),
    
    format_time(string(CustomTime3), '%FT%T.%f%z', T),
    writeln(CustomTime3),

    % Parse a custom time format
    parse_time('8:41 PM', '%I:%M %p', CustomParsedTime),
    write_term(CustomParsedTime, []),
    nl,

    % Format time components manually
    date_time_stamp(date(Year, Month, Day, Hour, Minute, Second, _, _, _), Stamp),
    format('~w-~|~`0t~d~2+~|~`0t~d~2+T~|~`0t~d~2+:~|~`0t~d~2+:~|~`0t~d~2+-00:00~n',
           [Year, Month, Day, Hour, Minute, Second]),

    % Demonstrate error handling in parsing
    catch(
        parse_time('8:41PM', '%a %b %d %H:%M:%S %Y', _),
        Error,
        (   write('Error: '), write(Error), nl)
    ).

This Prolog code demonstrates time formatting and parsing, similar to the original example. Here’s an explanation of the code:

We use the library(time) module for time-related operations in Prolog.
The get_time/1 predicate is used to get the current time.
format_time/3 is used for formatting time. It takes a format string similar to the C strftime function.
parse_time/3 is used for parsing time strings. It can handle various formats, including ISO 8601.
We demonstrate custom time formatting using different format strings.
For purely numeric representations, we extract the components of the time and format them manually using format/2.
Error handling in Prolog is demonstrated using the catch/3 predicate when attempting to parse an invalid time string.

To run this program, you would typically save it to a file (e.g., time_formatting.pl) and then consult it in a Prolog interpreter:

?- [time_formatting].
?- main.

This will execute the main/0 predicate and display the formatted and parsed times.

Note that Prolog’s approach to time handling is somewhat different from imperative languages. It uses predicates and unification rather than functions and return values. The error handling is also different, using Prolog’s exception mechanism.

Epoch in Prolog

Writing Files in Prolog

Learn X By Example

Title here

Time Formatting Parsing in Prolog