my @a = @{[do { local $_ = "fool\n"; chomp; $_ ; } ]}; 
print "@a"; ## prints "fool" 
$b = ${do { local $_ = "cool\n"; chomp; $_; }}; 
print "\n$b"; 
$c = ${do { local $_ = "cool\n"; chomp; $_; }}; 
print "\n$c";

#!/usr/bin/perl 
 
# This is casting an array reference to an array 
my @a = @{[do { local $_ = "fool\n"; chomp; $_ ; } ]};  
print "@a"; ## prints "fool"  
 
# The {} create an anonymous hash.  
# This is NOT a casting 
# $b = ${do { local $_ = "cool\n"; chomp; $_; }};  
 
# This sets $b to be a reference to an anonymous hash 
$b = {do { local $_ = "cool\n"; chomp; $_; }};  
print "\n$b";  
 
# The {} create an anonymous hash.  
# This is NOT a casting 
# $c = ${do { local $_ = "cool\n"; chomp; $_; }};  
 
# This sets $c to be the scalar of an array of  
# keys to an anonymous hash 
$c = keys(%{{do { local $_ = "cool\n"; chomp; $_; }}});  
print "\n$c"; 
 
# This set $c to the value of the number of used buckets 
# and the number of allocated buckets, separated by a slash. 
# http://perldoc.perl.org/perldata.html 1/4 down the page 
$c = %{{do { local $_ = "cool\n"; chomp; $_; }}};  
print "\n$c"; 
print "\n";

$ ./b.pl 
fool 
HASH(0x100804ff0) 
1 
1/8 
$