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Predicate time/1
Availability::- use_module(library(statistics)).(can be autoloaded)
Sourcetime(:Goal)
Execute Goal just like call/1 and print time used, number of logical inferences and the average number of lips (logical inferences per second). Note that SWI-Prolog counts the actual executed number of inferences rather than the number of passes through the call and redo ports of the theoretical 4-port model. If Goal is non-deterministic, print statistics for each solution, where the reported values are relative to the previous answer.
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LogicalCaptain said (2020-09-01T08:24:44):0 upvotes 0 0 downvotes
Picture of user LogicalCaptain.

This prints something like

% 4,623,232 inferences, 1.223 CPU in 1.229 seconds (99% CPU, 3780625 Lips)

But why aren't those values returned in variables?!?

They can't even be caught using with_output_to/2:

?- with_output_to(string(S),time(sleep(1))).
% 1 inferences, 0.000 CPU in 1.000 seconds (0% CPU, 24841 Lips)
S = "".

Time to go take a look at that code...

(Also, what exactly is a "logical inference" ... is it a clause call? LIPS seems to go back to marketing efforts made in the 80s during the 5th Generation project, it sounds a bit too high-level for Prolog.)