When you say "return @bar" Perl flattens @bar into a list.

That's what happens in _list_ context. If the sub is called in scalar context, @bar will also be in scalar context and thus return the number of elements in @bar.

sub foo {
    my @foo = qw(a b c d);
    return @foo;
}
sub bar {
    return qw(15 4 3 12);
}

print        foo(), "\n"; #   list context => abcd\n
print scalar foo(), "\n"; # scalar context => 4\n
print        bar(), "\n"; #   list context => 154312\n
print scalar bar(), "\n"; # scalar context => 12\n
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Explanation: a list returns its last element in scalar context, an array returns the number of elements in scalar context.

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
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