Yeah, I mentioned that. Here is one that fixes that and is actually simpler. (:

#!/usr/bin/perl -w
use strict;

use mapcar;

sub neighbors {
    my @coords= @_;
    my @digits= ( 0, -1, 1 );
    my @offset= (0) x @coords;
    return sub {
        my $i= 0;
        while(  2 < ++$offset[$i]  ) {
            $offset[$i]= 0;
            return   if  $#offset < ++$i;
        }
        return mapcar { $_[0] + $digits[$_[1]] }
            \@coords, \@offset;
    };
}

my $next= neighbors( 6, 2, -4 );
my @coords;
while(  @coords= $next->()  ) {
    print "( @coords )\n";
}
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