#!/usr/bin/perl
use warnings;
use strict;

use List::Util qw{ any };

sub flatten {
    my ($struct) = @_;
    if (ref [] eq ref $struct) {
        return map flatten($_), @$struct
    } elsif (ref \\"" eq ref $struct) {
        return $$struct
    } else {
        return \$struct
    }
}

use Test::More tests => 2;

my $ar = [ [ 'HEAD_goes_here', 'BODY_here' ],
           [ 'FOOT', 'FOOT', 'FOOT', 'FOOT' ] ];

my @flat = @$ar;
while ( any { ref [] eq ref $_ } @flat ) {
    @flat = map { ref []   eq ref $_ ? \(@$_) : \$_ } @flat;
    @flat = map { ref \\"" eq ref $_ ? $$_    : $_  } @flat;
}

is_deeply \@flat,
    [map \$_, qw[ HEAD_goes_here BODY_here FOOT FOOT FOOT FOOT ] ];

is_deeply [flatten($ar)],
    \@flat;