First, "$arr_ref_new = ( [1],[2],[3,4] );" can't possibly be what you want. You construct three arrays then proceed to discard two. (Why didn't you ask why you were getting "in void context" warnings?) So you're not clear on the inputs to your problem.

Second, you're not very clear on what output you want either.

I think you want:

my $aoa = [ [1],[2],[3,4] ];
my @flat = map { @$_ } @$aoa;  # @flat = (1,2,3,4)
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Update: Fixed variable name mismatch.

Insofar as I understand the (apparently edited) OP, a recursive approach also works (and is almost one line):

>perl -wMstrict -le
"my @a_refs = ([1], 2, [3, 4], [5, [6, [7, 8]]], 9);
 ;;
 sub flatten { map { 'ARRAY' eq ref() ? flatten(@$_) : $_ } @_ }
 ;;
 my @flattened = flatten(@a_refs);
 use Data::Dumper;
 print Dumper \@flattened;
"
$VAR1 = [
          1,
          2,
          3,
          4,
          5,
          6,
          7,
          8,
          9
        ];
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Note: This also works on the original example (Update (per GrandFather): as it was ultimately updated:)  ([1],[2],[3,4]) array.

The last line of the original code was:

$arr_ref_new = ( [1],[2],[3,4] ) ;
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True laziness is hard work

my $foo = [1,2,3];

# assign (1,2,3) to @bar
my @bar = @$foo;

# assign ([1],[2],[3]) to @baz
my @baz = map { [$_] } @$foo;
[download]