my @simpsons=("homer","bart","marge","maggie","lisa");
my @females=("lisa","marge","maggie","maude");

my %simpsons=map{$_ =>1} @simpsons;
my %females=map{$_=>1} @females;

# the intersection of @females and @simpsons:
my @female_simpsons = grep( $simpsons{$_}, @females );

# proof it works
print "Female Simpson:\t$_\n" foreach (@female_simpsons);

# the difference of @females and @simpsons

my @male_simpsons=grep(!defined $females{$_}, @simpsons);

# proof it works
print "Male Simpson:\t$_\n" foreach (@male_simpsons);
my %union = ();

# the union of @females and @simpsons
foreach(@females,@simpsons){
    $union{$_}=1;
}

my @union2 = keys %union;

# or just do this
# my @union = (@females, @simpsons);
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use Quantum::Superpositions;

my @a = (1,2,3,4,5,6,7,8,9,10);      # integers
my @b = (2,4,6,8,10,12,14,16,18,20); # doubled

my @unionAB        = sort { $a <=> $b } eigenstates( any(@a, @b) );
my @intersectionAB = sort { $a <=> $b } eigenstates( any(@a) == any(@b
+) );
my @differenceAB   = sort { $a <=> $b } eigenstates( any(@a) != all(@b
+) );
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This is inefficient, but I use it for intersection when I know I'm guaranteed small list sizes, and it's more valuable / pleasing to me to have a one-line solution:

the problem with that method is that your @isect can contain identical elements

for example,if @a=(1,2,3,4,2) and @b=(1,2,4), your @isect will be: (1,2,2,4)

before using this method you have to make sure each element is unique in both tab