#!perl! -w
use strict;
use Data::Dumper;

my @A = ( 'yahoo.com', 'altavista.com', 'yahoo.com/index.html' );
my @B = ( 'yahoo.com', 'webcrawler.com' );

# The task: make a @C such that @C = ( 'altavista.com' )

# dragonchild's solution:
my @C = map { my $x = $_; grep { $x =~ /\Q$_/i } @B } @A;
# produces ( 'yahoo.com', 'yahoo.com' )

# proper solution:
my @D = grep { 
	my $x = $_;
	my @matches = grep { $x =~ /\Q$_/i } @B;
	! @matches
} @A;

print Dumper [ \@A, \@B, \@C, \@D ];