Given where they are, it seems that now the major abstraction they are missing is type safety. Strict types that allowed a monadic structure would simplify this whole mess into a series of maps and folds.

Not only does this add the stricture of a compiler enforcing correct return types for all conditionals, it is also idiomatic of any language that supports this.

Having said all that, changing languages is rarely an option. Maybe this is the best solution given the tool available. If so, it demonstrates that maybe this tool isn't right for this job.