Perl - determine if an array is a subset of another array [duplicate]

Question

I have the following code. Can isSubset be written simpler without add-on CPAN modules?

my @possibleNames = ("adam", "chelsea");
my @actualNames = ("adam", "chucky", "chelsea");

sub isSubset {
    my ($littleSet, $bigSet) = @_;
    foreach (@{$littleSet}) {
        return 0 unless ($_ ~~ @{$bigSet});
    }
    return 1;
}

printf("%s\n", (isSubset(\@possibleNames, \@actualNames) ? "yes" : "no"));

Answer 1

One fairly efficient way to do it would be:

sub isSubset {
    my ($littleSet, $bigSet) = @_;
    my %hash;
    undef @hash{@$littleSet};  # add a hash key for each element of @$littleSet
    delete @hash{@$bigSet};    # remove all keys for elements of @$bigSet
    return !%hash;             # return false if any keys are left in the hash
}

Answer 2

my @possibleNames = ("adam", "chelsea");
my @actualNames = ("adam", "chucky", "chelsea");

my $is_subset = 0==grep !defined, map { @$_{@actualNames}=(1)x@actualNames; delete @$_{@possibleNames} } {};

But seriously, use Array::Utils::array_minus.