my $possibilities = 2 ** $N; # $N is number of dimensions
# @mypos is my coordinates.
for (1 .. $possibilities) { # using 0 would return my own position
 my $binary = sprintf '%b', $_;
 my $pad= '0' x ($N - length $binary);
 $binary = $pad.$binary;
 my @shift = split //, $binary;
 my @pos = map {$mypos[$_] - $shift[$_]} 0 .. $#mypos;
 push @neighbours, \@pos;
}