Thanks for the tip theorbtwo, definately a job for Quantum::Superpositions, a module I was unfamiliar with.

Now I'm not sure about the Old Bird's logic though. I suppose I'll take her at her word that all trees should be bread _and_ cheese, disallowing bread-only and cheese-only trees.

CheeseFoo

#!/usr/bin/perl

   use Quantum::Superpositions;

   if (all(@the_world) == $apple_pie and all(@the_seas) == $ink) {
      if (all(@the_trees) == all($bread, $cheese)) {
         $drink = <>;
      }
   }
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