Files
scryer-prolog/src/prolog/lib/time.pl
2020-04-19 22:44:48 +02:00

61 lines
1.6 KiB
Prolog

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Written April 2020 by Markus Triska (triska@metalevel.at)
Part of Scryer Prolog.
This library provides predicates for reasoning about time.
Reasoning about time stamps would be a useful addition, for example
by obtaining the current time, comparing and formatting it.
'$cpu_new' can be replaced by statistics/2 once that is implemented.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
:- module(time, [sleep/1, time/1]).
:- use_module(library(format)).
:- use_module(library(iso_ext)).
sleep(T) :-
builtins:must_be_number(T, sleep),
( T < 0 ->
throw(domain_error(not_less_than_zero, T))
; T > 0xfffffffffffffbff ->
throw(domain_error(not_great_than_0xfffffffffffffbff, T))
; '$sleep'(T)
).
time(Goal) :-
'$cpu_now'(T0),
Goal,
'$cpu_now'(T),
Time is T - T0,
( bb_get('$first_answer', true) ->
format(" % CPU time: ~3f seconds~n", [Time])
; format("% CPU time: ~3f seconds~n ", [Time])
).
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
?- time((true;false)).
% CPU time: 0.000 seconds
true
; false.
:- time(use_module(library(clpz))).
% CPU time: 2.762 seconds
true
; false.
:- time(use_module(library(lists))).
% CPU time: 0.000 seconds
true
; false.
?- time(member(X, [a,b,c])).
% CPU time: 0.000 seconds
X = a
; % CPU time: 0.002 seconds
X = b
; % CPU time: 0.004 seconds
X = c
; false.
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