types                = make(map[reflect.Type]gobType, 32)
	idToTypeSlice        = make([]gobType, 1, firstUserId)
	builtinIdToTypeSlice [firstUserId]gobType // set in init() after builtins are established
)

func idToType(id typeId) gobType {
	if id < 0 || int(id) >= len(idToTypeSlice) {
		return nil
	}
	return idToTypeSlice[id]
}

func builtinIdToType(id typeId) gobType {