Spent the night trying to figure out why the braces subroutine works with dereferencing with braces and the no_braces subroutine halts on execution with the error, "Not an ARRAY reference." Could anyone give an explanation why Perl is preferring the dereferencing with braces and throwing a run time error when they are not included? Tried searching around and people seem to treat both methods as being synonymous. Thanks!

#!/usr/bin/perl

use strict;
use warnings;

my @a1 = qq/one two three four five/;
my @a2 = qq/six seven eight nine ten/;
my %hash;

$hash{key_1} = \@a1;
$hash{key_2} = \@a2;

braces(\%hash);
no_braces(\%hash);

sub braces {

    my $hash_ref = shift;

    foreach my $key (keys %$hash_ref) {
        foreach my $value (@{$hash_ref->{$key}}) { #Curly braces
            print "Key: $key, Value: $value\n";
        }
    }
}

sub no_braces {

    my $hash_ref = shift;

    foreach my $key (keys %$hash_ref) {
        foreach my $value (@$hash_ref->{$key}) { #No curly braces
            print "Key: $key, Value: $value\n";
        }
    }
}
[download]