use strict;
use warnings;
use Data::Dumper;

my $data;
{ local $/; $data = <DATA> }
$data =~ tr/}{/][/;
$data =~ s/\s*(.*?)\s*=>\s*(.*?)\s*,/"$1","$2",/g; # warning: simplistic quoting

my $aref;
eval "\$aref=$data";

sub array2hash {
		my $aref = shift;
		return $aref if "ARRAY" ne ref $aref;
		die "Cannot turn array with odd number of elements into hash.\n" if @$aref %2;
		my $href = {};
		for (0..@$aref/2-1) {
				$aref->[2*$_] .= "_" while( exists $href->{$aref->[2*$_]} );
				$href->{$aref->[2*$_]} = array2hash( $aref->[2*$_+1] );
		}
		return $href;
}

my $href = array2hash $aref;
print Dumper $href;

__DATA__
{
  alpha => {
    beta => {
      gamma => theta,
      delta => lambda,
    },
    beta => {
      gamma => zeta,
    },
  },
},