3 ms·

Ha, excellent point. Thanks.

• tom_mellior 9y ago
  OK, so now we are ready to answer the great-great-grandparent's question: > Is SWI-Prolog really faster than CLisp? No. At least not on naive Fibonacci. [1]> (defun fib (n) (if (<= n 1) 1 (+ (fib (- n 1)) (fib (- n 2))))) FIB [2]> (compile 'fib) FIB ; NIL ; NIL [3]> (time (fib 38)) Real time: 6.730412 sec. Run time: 6.732 sec. Space: 0 Bytes 63245986 The project's GitHub page makes pretty much all the mistakes you can make when benchmarking: Comparing programs that are not equivalent and with wildly uncomparable optimization settings. There is an almost incomprehensible blurb at the end of https://github.com/TeamSPoon/wam_common_lisp https://github.com/TeamSPoon/wam_common_lisp that (I think) tries to argue that you should not turn on optimization in Lisp because it costs more than you gain. I disagree.
  • zmonx 9y ago
    Thank you for these benchmarks! For a fair comparison, one should however also take into account that SWI-Prolog is among the slower Prolog systems. I therefore recommend to also use a faster Prolog system. For example, I used the following Prolog translation of your code and ran it in GNU Prolog: n_fib(N0, F) :- ( N0 =< 1 -> F = 1 ; N1 is N0 - 1, N2 is N0 - 2, n_fib(N1, F1), n_fib(N2, F2), F is F1 + F2 ). On my machine configuration, GNU Prolog is more than thrice as fast as SWI-Prolog (even with -O) for: | ?- n_fib(38, F). F = 63245986 GNU Prolog in fact compiles to native code. You can test this by putting the code into a file, say fib.pl, and compiling it with the GNU Prolog compiler using: $ gplc fib.pl You can then run it with ./fib and invoke the above query.