----- Mail original ----- > De: "Maurizio Cimadamore" <maurizio.cimadam...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr>, "valhalla-spec-experts" > <valhalla-spec-experts@openjdk.java.net> > Envoyé: Jeudi 9 Mai 2019 12:00:12 > Objet: Re: It's not safe until it's in the coffer
> Another oddity, that I find hard to explain away: > > Coffer<String> ~= String > > This seems to be a bad property, as you have two types to name the same > thing. > > You could, in principle, say that the type parameter of Coffer is > restricted to... values. yes, the type argument of a Coffer is restricted to an inline class, i've forgotten to mention that, thanks. > > But here's the second, pedagogical oddity: Coffer<Value> looks an awful > lot like a specialized generic type. I think people will be surprised in > seeing that this magic types works, while the types they want > (List<Value>) does not. Yes, it's surprising but it has nothing to do with Coffer or V? but with the fact that a T can be nullable and an inline class is not. Note that the error message saying that List<Value> doesn't work, can suggest that List<Coffer<Value>> may work (at least for LW10). Now, yes, it looks like a specialized generic type and i think it's fine given we want to introduce specialized generics types in LW3000. > > Besides... > > List<Coffer<Value>> > > is reeeallly verbose, do we really want to read code like that? yes, it's verbose by design. > > At the language level, the number of exceptions this will require all > over the place, from generic well-formedness to inference (imagine > passing a 'Value' where a Coffer<Z>) is expected, that, while I can > sympathize with your opening position of '?' being confusing, it seems > the proposed cure is worse than the disease :-) I don't think so, here you are supposing, i believe, that the inference has to be changed because inferring Z as an indirect object is not useful. But we don't have to change the inference, the same way when you have a T... you don't have a special inference rule because creating an array of parameterized type is unsafe, the idea is to do the same inference algorithm and at the end, you emit an error if Z is not an inline class. So yes you have some rules around creating a Coffer but they are far less invasive than adding a new union type V? in the type system. > > Maurizio Rémi > > > On 08/05/2019 23:12, Remi Forax wrote: > > There are two oddities:
