To give you the full picture, it is possible to pass arrays as parameters and circumvent the flattening of those arrays.

That involves using subroutine prototypes and is probably one of the few acceptable uses of prototypes .

It goes as follows:

use Modern::Perl;

sub two_arrays (\@\@) {
    my @first  = @{$_[0]};
    my @second = @{$_[1]};
    say "First array:  @first";
    say "Second array: @second";
}

my @one = qw/een twee drie/;
my @two = qw/nung song saam/;

two_arrays(@one, @two);
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Output:

First array:  een twee drie
Second array: nung song saam
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The prototype (\@\@) means that this subroutine takes two arrays as parameters and a reference to those two arrays will passed to the sub. This "referencing" will happen automatically and of course it means that you must dereference it inside of your sub.

It is not the usual or expected mode of operation of using subroutines and you better document this very clearly or people will get quite confused. But it is there if you want it.