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> On Apr 23, 2018, at 4:22 PM, Kevin Bourrillion <kev...@google.com> wrote: > > On Mon, Apr 23, 2018 at 12:00 PM, Guy Steele <guy.ste...@oracle.com> wrote: >>> On Apr 23, 2018, at 2:58 PM, Kevin Bourrillion <kev...@google.com> wrote: >>> >>>> On Mon, Apr 23, 2018 at 11:20 AM, Guy Steele <guy.ste...@oracle.com> wrote: >>>> >>>> (1) We have moved toward allowing “arrow versus colon” to be a syntax >>>> choice that is COMPLETELY orthogonal to other choices about the use of >>>> `switch`. If this rule is to hold universally, then any switch statement >>>> or expression should be convertible between the arrow form and the colon >>>> form using a simple, uniform rule. >>>> >>>> (2) In switch expressions we want to be able to use the concise notation >>>> `case a, b, c -> s;` for a switch clause. >>>> >>>> (3) From (1) and (2) we inexorably conclude that `case a, b, c: break s;` >>>> must also be a valid syntax. >>>> >>>> (4) But we could also have written (3) as `case a: case b: case c: break >>>> s;` and we certainly expect them to have equivalent behavior. >>>> >>>> (5) From (1) and (4) we conclude that we ought also be to be able to write >>>> `case a -> case b -> case c -> s;`. >>> >>> Not necessarily, if one simply views (4) as being an artifact of colonform >>> switch's capacity for fall-through, which we know should not carry over. >>> (Although we technically don't use the term "fall-through" in this >>> no-intervening-code case, it works the same way and many people do think of >>> it that way.) >> >> You could view it that way—but such a view is incorrect, going back to JLS1. > > To be more clear, I wasn't trying to make a statement about what is correct > or incorrect by the spec. (On such matters I will always be deferring to the > rest of you!) > > My claim is just that it is not hard for a user to make sense of why `case A: > case B: x` would work in colonform yet `case A -> case B -> x` might not work > in arrowform. These don't necessarily feel contradictory. A user may simply > understand that since colonform's design is made to support fall-through, > that became an obvious way that it could address multiple labels as well, > whereas the same does not apply in arrowform. Fair enough. > Okay, so it's a "folk model". I think that neither makes it automatically > good nor automatically bad. > > To the user, I believe that the ability to choose `case A -> case B ->` is an > unnecessary choice and feels like the same kind of baggage that I'd hoped to > leave behind when moving to arrowform. Yep. Agreed that you would almost never want to use it. But it would give me a warm, fuzzy feeling to know it’s lurking there for the few times you really need it
