sub generateMultiplier {
    my( $byWhat )= @_;
    return sub {
        my( $toBeMultiplied )= @_;
        return $toBeMultiplied * $byWhat;
    }
}

my @list= ( 1, 2, 3, 5, 7, 11 );
my $doubler= generateMultiplier( 2 );
my $tripler= generateMultiplier( 3 );
my @twice= map $doubler->($_), @list;
my @thrice= map $tripler->($_), @list;