0: #!/usr/bin/perl -w
1: #
2: # Three map one-liners for dealing with lists
3: 
4: # Removing duplicates
5: 
6: my @list1 = ('a', 'b', 'c', 'b', 'a', 'b', 'd', 'e');
7: my @list2 = ('x', 'y', 'y', 'z');
8: my @dedupedlist = keys %{{ map { $_ => 1 } (@list1, @list2) }};
9: print "@dedupedlist\n";
10: 
11: ###################################
12: 
13: # Determining whether an item is in a list
14: 
15: my $item = 'aaa';
16: my @list = ('aaa', 'bbb', 'ccc', 'ddd', 'eee');
17: 
18: if ({ map { $_ => 1 } @list }->{$item})
19: {
20:     print "Yes!\n";
21: }
22: else
23: {
24:     print "No!\n";
25: }
26: 
27: ###################################
28: 
29: # (The finale...)
30: # 'Diff' two lists
31: 
32: my @lista = ('R', 'o', 'b', 'e', 'r', 't');
33: my @listb = ('e', 'r', 't');
34: my @difflist =  map {  {map { $_ => 1 } @listb}->{$_} ? ()  : $_  } @lista;
35: print "@difflist\n";
36: