I thought subroutines can accept arrays then passed to @_

That sentence is a contradiction. Array element can only be scalars, so @_ can't contain an array. It can only contain a reference to one since a reference is a scalar.

In

foo(@a)
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@a evaluates to its content, and those are used as the arguments. The above is the same as

foo($a[0], $a[1], $a[2], $a[3]);
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The plan was to use this code segment once working in a larger context.

Careful

my $old_x = [qw( a b c )];
$memd->set(x => $x);
my $new_x = mem_get('x');  # $new_x = 3 !?
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