typical

te the field to required. Typical's asymmetric fields offload the burden of having to do that manual confirmation onto the type checker. 2. For unions, Avro offers no equivalent of optional or asymmetric cases. If you add a new case, you better not use it until all readers can handle it, and the type checker won't enforce that. For enums, the solution of having default values is unsatisfactory, because not every type has a suitable default. In practice, this usually means adding a catch-all default that is only used to signal an unrecognized input, but then what is a reader supposed to do with that? With Typical, if a writer introduces a new optional or asymmetric case, it must then provide an appropriate fallback to use when the new case isn't recognized by readers. For example, if a new specific type of error is introduced (e.g., with a stack trace), the fallback might be a more general type of error (e.g., with only an error message) that readers already know how to handle. If the new case is asymmetric, then you know readers can handle it, so once its rolled out you know it's safe to subsequently promote the case to required (so that writers no longer need to provide a fallback). Here I've only discussed the challenges with adding new required fields/cases, but you run into similar trouble when removing them. This section of the README discusses all the pitfalls: https://github.com/stepchowfun/typical#required-optional-and...