You can save a bit of memory by first grepping for defined elements inside each array, and then combining them: 

my @flat = map { grep defined, @$_ } @{$aoa};

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That way the "big" list with all the elements, including the undefs, isn't fully created in the first place.

Perl 6 - second systems done right

In reply to Re: Flatten sparse AoA by moritz
in thread Flatten sparse AoA by FloydATC

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