Because that would be... illogical, captain.

There is a good logical reason for not embedding packages inside a script file (such as, modules are supposed to be re-usable, but they certainly aren't when they're embedded in a script), but there are also some syntactic issues that you'll run into. (Aside: there is a good reason for being able to embed scripts in a module -- test cases.)

If I remember correctly, use expects a .pm file (there may be some way to override this, but I don't know it). So when you say use XX::Blah perl goes looking for XX/Blah.pm in all of the directories included in @INC (which usually includes '.'). I doesn't matter that the package is defined in that script, Perl doesn't know to look for it there because it's not a .pm file. You might be able to futz around with require, but I seriously doubt that that will improve things for you.

I tried this little test:

package Foo;

sub test {
        return "test";
}

1;

package main;

use Foo;

print STDOUT Foo::test();

exit 0;
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No dice. I even played around with package main::Foo just to make sure, but still no dice.

But if you place package Foo in the file Foo.pm then the script compiles perfectly and prints out "test" before exiting.

Alternately, if you remove the use then you can do what you want as follows:

package Foo;

sub test {
        return "test";
}

1;

package main;

print STDOUT Foo::test();

exit 0;
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HTH