I write Scheme code as if it had ADTs, e.g.

    (match payment
      [('invoice address     ) (foo address     )]
      [('card    card-details) (bar card-details)])

As you say, there's no exhaustiveness check; plus the language won't guarantee that the product types are adhered to. For example, someone might give us `('invoice card-details)` and the language wouldn't complain.

Racket's contract system can help with this; although it's very slow.