Perl complex data structures example

complex.pl

use 5.010;
use warnings;
use strict;

use Data::Dumper;

# If you have access to CPAN, check out Data::Printer
# https://metacpan.org/module/Data::Printer

## build a list of hashes
my @list_of_hashes;
push @list_of_hashes, { foo => "bar", 1 => "hi", };

## iterate over list; there is more than one way to do this, naturally
foreach my $hash ( @list_of_hashes ) {
  foreach my $key ( keys %{ $hash } ) {
    say "key: $key => value: $hash->{$key}";
  }
}

## build a hash of hashes
my %hash_of_hashes;
$hash_of_hashes{"some_key"} = { hello => "world!" };

say Dumper %hash_of_hashes;

# or

my $hash_ref;
$hash_ref->{"some_key"} = { hello => "world!" };

say Dumper $hash_ref;

say $hash_ref->{"some_key"}->{"hello"};

# build a hash of lists of lists
#
# yes, you can keep going on this if you want, but it might be silly

my %hash_of_lists;

push @{ $hash_of_lists{"some_key"} }, [ "foo", "bar", 1 ];

# prints a list with sublist 'foo', 'bar', 1
say Dumper $hash_of_lists{"some_key"};

# prints 'bar'
say $hash_of_lists{"some_key"}[0]->[1];