Opting into totality
brian.goetz at oracle.com
Wed Aug 26 13:42:22 UTC 2020
Note that this:
On 8/25/2020 7:53 PM, Brian Goetz wrote:
> `default <deconstruction pattern>` means the same thing as `case <deconstruction pattern>`
> but it is a static error if the <deconstruction pattern> is not_weakly_ total on the type of the selector
when combined with
> I’ll add that in the last case, it is as if there is an implicit `case null: throw`.
comports nicely with the planned semantics for pattern assignment:
P = e
requires that P be (weakly) total on the static type of e, and is
permitted to NPE when e is null. When P is a total type pattern or an
any pattern, this degenerates to normal variable declaration +
Box<String> b = ...
String s = b // type error
Box bb = b // fine, total
Box(Object o) bb = b // fine, weakly total, throws NPE when b = null
I will consolidate all of this today into a new message.
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