So it's a matter of merging hashes? You could use an iterator, perhaps something like the following: 
#! /usr/bin/perl  -l

my $zoo = {
  Mountain => { Dragon => 'Deadly', Troll => 'Deadly', Nymph => 'Oread
+', Snake => 'Deadly' },
  Cave => { Dragon => 'Deadly', Spider => 'Poisonous', Troll => 'Deadl
+y', Ogre => 'Deadly' },
  Forest => { Elf => 'Dark', Troll => 'Deadly', Nymph => 'Alseid', Spi
+der => 'Hairy' },
  Lake => { Nymph => 'Naiad', Snake => 'Poisonous', Serpent => 'Deadly
+' },
  Sea => { Kraken => 'Monstrous', Serpent => 'Monstrous' }
};

sub each_uniq {
  my @refs = @_;
  my %seen = ();
  sub {
    while (@refs) {
      my @pair = each %{$refs[0]} or shift @refs and next;
      return @pair unless $seen{$pair[0]}++;
    }
    return;
  }
}

my $iter = each_uniq(values %$zoo);
print join(", ", $iter->()) for 1..5;

[download]

Update. I read the previous questions monkini has asked, and it would appear the problem is largely unrelated to questions asked. From what I gather, he has a number of clusters each with a number of (labelled) points, and distances between points given. The problem apparently is to list the pairs of points in a cluster sorted by their distance, for each cluster separately. If so, the solution is to map clusters to points (HoA), iterate, slice map slice sort the HoH, print.

In reply to Re: Until loop / unique by oiskuu
in thread Until loop / unique by monkini

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