Compare Language::Prolog::Yaswi and AI::Prolog

#!/usr/bin/env perl
use strict;
use warnings;
use diagnostics;

use Benchmark;
use AI::Prolog;
use Language::Prolog::Yaswi qw(:load :query);
use Language::Prolog::Sugar
    vars => [qw(X Z)],
    functors => {travelFromTo => 'travelFromTo'};

my $database = <<'END_PROLOG';
directTrain(saarbruecken,dudweiler).
directTrain(forbach,saarbruecken).
directTrain(freyming,forbach).
directTrain(stAvold,freyming).
directTrain(fahlquemont,stAvold).
directTrain(metz,fahlquemont).
directTrain(nancy,metz).

travelFromTo(X,Y) :- directTrain(X,Y).
travelFromTo(X,Z) :-
    directTrain(X,Y),
    travelFromTo(Y,Z).
END_PROLOG

swi_inline <<"EOP";
$database
EOP

sub by_yaswi {
    swi_set_query(travelFromTo(X, Z));
    while (swi_next) {
    swi_vars(X), swi_vars(Z);
    }
    return;
}

my $prolog = AI::Prolog->new($database);
sub by_ai_prolog {
    $prolog->query("travelFromTo(X,Z).");
    while (my $result = $prolog->results) {
    my @results = @{$result}[1..2];
    }
    return;
}

timethese(1000, {
    "by yaswi" => 'by_yaswi()',
    "by ai prolog" => "by_ai_prolog()",
      });