my @set = qw(foo bar baz);

# use glob to expand all permutations
my @perm = glob( join(",", ("{".join(",",@set)."}") x @set) );

print "Permutations:\n";
print "$_\n" for @perm;

# filter out duplicates
my %uniq;
my @comb = grep !$uniq{$_}++, map join(",",sort split(/,/,$_)), @perm;

print "Combinations:\n";
print "$_\n" for @comb;