You can't pass arrays (or hashes) to subs, only a sequence of zero or more scalars. There is no difference between

f(@a)
[download]

and

f($a[0], $a[1], $a[2], ...)
[download]

so you can't distinguish

my @empty;
f(@empty)
[download]

from

f()
[download]

---

At best, you can use prototypes to change what scalars are passed to a sub.

sub f(;\@)
[download]

will allow

f(@a)     # Calls &f(\@a)
[download]

and

f()       # Calls &f()
[download]

but not

f($x, $y)
[download]

What you want to achieve, however, can't be achieved using prototypes. You'd have to use something like Devel::CallParser.