Does any representation deserve to be singled out as the "real regex"? I'd have picked the abstract syntax tree. A bunch of constructor calls are closer to that

Does any representation deserve to be singled out as the "real regex"? I'd have picked the abstract syntax tree. A bunch of constructor calls are closer to that. (Yes, the Perl regex syntax has some advantages, and I'm only objecting to what you're calling it. Though it's also true that a tree structure has advantages over a string: for instance, you don't have to parse it to manipulate it.)