Why not..

I didn't check the relative precedence of "or" and ",". I also liked the visual grouping.

Or even

No, it doesn't work. It returns before evaluating warn.

It seems that unless I want to create my own perl distro, there's no way to do as JavaFan suggests

What JavaFan suggested works as is. If you mean to make it pretty... The best way probably would require language-level support.

we can't just add another function to the language at compile time

I guess it depends on what you mean by function. Out of context, I'd say that's not true.