[antonovka2]

Heterogeneous collections, discriminated unions, and GADTs can be implemented easily in either thrift or protobuf by leveraging inclusion of custom type-tagged messages/data.

However, while the encodings are absolutely sufficient to represent these data structures -- if you so choose -- my experience dictates that keeping serialized messages typed and as simple as possible is advantageous from the perspective of long-term maintenance and interoperability.

[blasdel]

Of course you can implement custom type-tagged blobs, but that's not using thrift or protobufs -- it's your own nebulous SOAP-style bullshit.

[antonovka2]

They're not "blobs" if they are also protobuf/thrift messages themselves.

[blasdel]

That's certainly cleverer, but it's still a nested user-implemented unsound type-system.