What's wrong with the "less helpful" template?

That is the interesting part. And it surprises me that I have never been caught by this in my years of occasional programming. I am still chewing on that aspect.

Both approaches return the same result.

Not quite, your tests are flawed. I wanted references to the same memory objects ("thingie" is out of style?) so running @flat through both your and my code is suspect on its face. When I comment out the while loop I don't get a happy result.

On a side note: In the "not-thinking" part I started on a recursive solution; when I hit some snags and applied some thought map seemed a clear win. I should study the methods to go from one to the other: iter. vs. recurs.

Using a shorter array:

my $ar = [ [ 'a', ], [ 'b, 'c', ], ];
my $flat = flat( $ar );
print Dumper $ar, $flat;
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$VAR1 = [
          [
            'a'
          ],
          [
            'b',
            'c'
          ]
        ];
$VAR2 = [
          \$VAR1->[0][0],
          \$VAR1->[1][0],
          \$VAR1->[1][1]
        ];
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