> that specific example is wrong This will be discovered at compile time if you use immutability & types like the article suggests. > So the assumption that y

> that specific example is wrong This will be discovered at compile time if you use immutability & types like the article suggests. > So the assumption that you either are loading XOR have data XOR have an error does not hold. If you design render() to take actual Userdata, not LoadingUserdata, then you simply cannot call render if it's not loaded. The way to produce unspecified behaviour is to enable nulls and mutability. Userdata{..} changing from unloaded to loaded means your render() is now dynamically typed and does indeed hit way more states than anticipated.