Scryer Prolog documentation

Module time

:- use_module(library(time)).

This library provides predicates for reasoning about time.


Yields the current system time T in an opaque form, called a time stamp. Use format_time//2 to describe strings that contain attributes of the time stamp.

format_time(FormatString, TimeStamp)//

The nonterminal format_time//2 describes a list of characters that are formatted according to a format string. Usage:

   phrase(format_time(FormatString, TimeStamp), Cs)

TimeStamp represents a moment in time in an opaque form, as for example obtained by current_time/1.

FormatString is a list of characters that are interpreted literally, except for the following specifiers (and possibly more in the future):

%Y year of the time stamp. Example: 2020.
%m month number (01-12), zero-padded to 2 digits
%d day number (01-31), zero-padded to 2 digits
%H hour number (00-24), zero-padded to 2 digits
%M minute number (00-59), zero-padded to 2 digits
%S second number (00-60), zero-padded to 2 digits
%b abbreviated month name, always 3 letters
%a abbreviated weekday name, always 3 letters
%A full weekday name
%j day of the year (001-366), zero-padded to 3 digits
%% the literal %


   ?- current_time(T), phrase(format_time("%d.%m.%Y (%H:%M:%S)", T), Cs).
      T = [...], Cs = "11.06.2020 (00:24:32)".


The maximum admissible time span for sleep/1.


Sleeps for S seconds (a floating point number or integer).

statistics(?Keyword, ?List)

Preliminary support for statistics/2, yielding timing information. The only supported Keyword is runtime. The first element of List is the CPU time in milliseconds, the second element is currently not supported.


Reports the execution time of Goal.