anchor.diff:    when is_atom(Type) ->
       data_field(capnp_type_info(Type), Offset).
   
  -list_field_type(Type) ->
  +list_field_type(List) ->
  +    Type = schema(get, elementType, List),
       {list, 
        case schema(get, Type) of
            void -> void;
  
positive.code:     {binary_to_atom(schema(get, name, Field), latin1),
       compile_struct_field_type(schema(get, Field))}.
  
  compile_struct_field_type({nonGroup, Field}) ->
      Type = schema(get, type, Field),
      compile_field(schema(get, Type), schema(get, offset, Field));
  compile_struct_field_type({group, Id}) ->
  
negative.code: capnp_type_info(uint64) -> {uint64, 64};
  capnp_type_info(float32) -> {float32, 32};
  capnp_type_info(float64) -> {float64, 64};
  capnp_type_info(text) -> {text, 8};
  capnp_type_info(data) -> {data, 8};
  capnp_type_info(Other) -> throw({unknown_capnp_type, Other}).
      
  data_field(void, _Offset) -> void;
  data_field({Type, 1}, Offset) ->
  