Why would you want such a thing?

Probably the simpest example I can think of is when you "need" to pass more than one array or hash (or one of each) to a function. Then you need to pass a reference, and sometimes you are either getting the array from a function or want to hard code it. So you have...

# Passing array refs from function returns...
foo([split(',', $a)], [split('/', $b)]);

# Passing hard coded data (used in CGI etc.)
bar([1..4],
    { 1 => "foo", 2 => "bar", 3 => "abcd", 4 => "xyz"});
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What's the scope on an anonymous thingie?

Probably the easiest thing to do is think of them as named variables, but the names are not in scope, so...

# "anonymous" reference to array of 8
my $foo = [1..8];

## Is the same as...
my $foo = undef;

# New scope...
{ # Array of 8
  my @foo = (1..8);
  # Create reference to array of 8
  $foo = \@foo;
}
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In both cases doing a $foo = undef; will get rid of the last reference to the array.