Maybe you will need to adapt your logic then.

If you want two things, but your other code can only handle a single thing, one or the other has to give.

My first approach would be to only call eval on the first thing if an arrayref is returned.

Other rules doing && or ! or || on this result would not be affected by this, but they might also need to be adapted to cope with the result not being a single string.

Let me note that you still have not shown us any workable example of what you have and what you want which is not amenable to a simple change like the one I outlined. My personal recommendation from having written half-assed parsers/program generators is to separate parsing the code from generating the output. Most approaches work on the resulting parse tree to restructure the tree according to simple rules and only after the (one or more pass off) restructuring generate the code from the tree.