Proposal: Elvis and Other Null-Safe Operators

Stephen Colebourne jodastephen at
Thu Mar 19 10:18:32 PDT 2009

Neal Gafter wrote:
> On Thu, Mar 19, 2009 at 1:26 AM, Jacek Kolodziejczyk
> <jacek.p.kolodziejczyk at> wrote:
>> In my opinion the most obtrusive part in the current state of proposals
>> is assumption that the invocation on null object should always return null.
>> If I understand it correctly the following would break at runtime,
>> because null cannot be assigned to boolean:
>>   List list = null;
>>   boolean b = list?.isEmpty();
> That would be a compile-time error because of the incompatibility
> between null and boolean.
The intention is that you can write a combination to handle this with 
the submitted Coin proposal:

List list = null;
boolean b = list?.isEmpty() ?: true;


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