Just a guess, but maybe you're just not looking at the return value the right way. 
 my $iter = permutations(\@data);
 while (my $p = $iter->next) {
     print "@$p\n";
 }

[download]
Trouble is, this will take a VERY long time to complete if @data is large.

In reply to Re: Longest Increasing Subset by Anonymous Monk
in thread Longest Increasing Subset by gilthoniel

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