Display the execution times for each goal of a predicate clause

Question

I want to see the execution time inside goals of predicate with SICStus Prolog.

Example :

pred :-
   goal1,
   time         


        

Answer 1

I'd like to add two thoughts:

1. Prolog allows for backtracking, so goals may succeed more than once.

   What's the "runtime" you are interested in?

   • Only the work for computing the previous answer?
   • Or rather the total time?

2. Use statistics/2, but don't do it directly. Instead, use an abstraction like call_time/2.

Sample query:

?- call_time((permutation([a,b,c,d,e,f,g,h,i],Xs),Xs=[_,_,g,f,e,d,c,b,a]), T_ms).
   Xs = [h, i, g, f, e, d, c, b, a], T_ms = 304
;  Xs = [i, h, g, f, e, d, c, b, a], T_ms = 345
;  false.

Notice that call_time/2 succeeds twice and T_ms measures total runtime up to this point.