acmp again !

Brian Goetz brian.goetz at
Thu Feb 21 01:48:09 UTC 2019

> It doesn't match my experience, currently people have no expectation of what == means on a value type, if you explain that a value type has no identity, that == doesn't work on a value type, most people are ok with that.

I think this is fantasy.

Value types are OBJECTS.  People think they know what == means on an 
Object, and for most users, the word "identity" does not come to mind.  
Further, we've told people that "values have only state, no identity -- 
if two values have the same state, they are the same." For such values 
not to be == will be astonishing.


      value class UnsignedInt {
         public static UnsignedInt ZERO = ...

         private int i;

         public static add(UnsignedInt a, UnsignedInt b) { ... }

     UnsignedInt x = ...
     if (x != UnsignedInt.ZERO) { ... }

People will never, ever, ever get used to the idea that test is always 
false.  Its a fantasy to think otherwise.  And the WHOLE POINT of 
L-World is to allow people to not sweat the small details between values 
and refs.  This is asking them to be acutely aware all the time.

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