Yeah, an extra layer of type indirection for expressing various implicit encodings is useful for e.g. dates My point overall is that there is tonnes of prior a

Yeah, an extra layer of type indirection for expressing various implicit encodings is useful for e.g. dates My point overall is that there is tonnes of prior art for compile time reflection libraries in c++ for this kind of thing. Boost has MPL, Fusion and Hana for starters. All of these have visitor patterns and algorithms out of the box. You originally said you hadn't found anything quite like it for unmanaged languages...but people have been doing this for decades at this point. In general I'm no longer a fan of the "encode the schema directly in C++" approach if the data i'm interfacing with actually has a schema.