I don't think I ever said it wasn't code, I said it wasn't "backend code". We've exchanged some config (sure, basically an AST) for writing some express/django/rails middleware. I'd much rather check authentication status by writing "{"!=", [request.auth, null]}" than writing more backend code, especially if someone else has done a bunch of the work for me.

That said, I'd argue this notation probably isn't a super concise representation for config over code. Implementing a JS evaluator so you could instead write "request.auth != null" and having JS like expressions is easier than the Prefix notation. Cool idea nonetheless!