> Version 2 just added a new required email field to the person record. In mutable schema systems, adding a new required field is universally forbidden. The API guidelines for Google, Microsoft and Zalando all ban the practice. Protobuf even marks the required keyword a hazard developers must avoid. These rules exist because a single definition is forced to serve every document ever written against it. TSON removes this burden because schemas are immutable. A version is simply a new document with a new hash. Two contracts coexist at full strength, and employee composing person inherits the new requirement in the same declaration.

I don't understand how this helps. That just means I have dozens of schemas for the same data set. How is that better? I'd rather have one lowest common denominator schema for the entire data set and be forced to validate.

I mean I guess because the data blob specifies its own schema I can use that schema to ensure the blob is valid but then what. What is my code that processes this data supposed to do? `if(schema1) { ... } else if(schema2) { ... }`. How is that better?