Checking if a string is null

[Manfred Nowak]

Bruno Medeiros wrote

> Erm, "all elements" is not in any different than "for all x in
> ...". 
[...]
> Ok, the relationalExpression, according to that spec quote, does
> seem to be restricted to arrays with one or more elements. But
> that's just the relationalExpression so far, it's not the case for
> the identityExpression or the equalityExpression.


Maybe, but i am currently not interested in evaluating this, because 
the definitions are underspecified anyway:

1 the definition for equalityExpression refers to a common base type,
: which is unspecified for arrays according to the definition of
: base type in type.html. 

2 the definition for identityExpression refers to the undefined
: relation `same' for the elements of arrays, which may be equality,
: equivalence or something completely different.  


> one expects it to have the same properties
> that a proper opEquals should (such as these: 
> http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Object.html#equal
> s(java.lang.Object) ).

That definition uses the phrase "most discriminating possible 
equivalence relation". I believe that types exist for which such a 
relation is not uniquely determined. Do you have a proof or a reference  
for the contrary?

-manfred