#!/usr/bin/perl -w
#
# Three map one-liners for dealing with lists

# Removing duplicates

my @list1 = ('a', 'b', 'c', 'b', 'a', 'b', 'd', 'e');
my @list2 = ('x', 'y', 'y', 'z');
my @dedupedlist = keys %{{ map { $_ => 1 } (@list1, @list2) }};
print "@dedupedlist\n";

###################################

# Determining whether an item is in a list

my $item = 'aaa';
my @list = ('aaa', 'bbb', 'ccc', 'ddd', 'eee');

if ({ map { $_ => 1 } @list }->{$item})
{
    print "Yes!\n";
}
else
{
    print "No!\n";
}

###################################

# (The finale...)
# 'Diff' two lists

my @lista = ('R', 'o', 'b', 'e', 'r', 't');
my @listb = ('e', 'r', 't');
my @difflist =  map {  {map { $_ => 1 } @listb}->{$_} ? ()  : $_  } @lista;
print "@difflist\n";