Zero values can, for the most part, be caught with a custom UnmarshalJSON implementation (and the new UnmarshalJSONFrom interface ought to remove most of the pe

Zero values can, for the most part, be caught with a custom UnmarshalJSON implementation (and the new UnmarshalJSONFrom interface ought to remove most of the performance penalty associated with that). The one problem is what to do when the field is missing entirely, because then UnmarshalJSON(From) will never be invoked. I have been thinking about suggesting a new struct field tag for JSON parsing: `json:',required'` that throws an error when the struct field is absent in the respective JSON object. The artifice is mostly in how to phrase that proposal in a way that makes it more likely for the Go devs to accept it. If I just come in like "I hate zero values", that may have some truth to it, but it's not going to be conducive to the discussion going the way I want.