Re: Covariant Return Types

[email protected] wrote:

>Quoting Daniel Bonniot <[email protected]>:
>
>  
>
>>>   package a;
>>>   class A { }
>>>   class B extends A { }
>>>   A self(A a) = a;
>>>   B self(B b) overrides A self(A) = b;
>>>
>>>   void main(String [] args) {
>>>       let x = self(A); // syntax?
>>>       let y = self(B); // syntax?
>>>       println(x == y); 
>>>   }
>>>
>>>Do I get "true" or "false"? 
>>>
>>>      
>>>
>>You get: "A is not a value" a the first line with the comment :-)
>>
>>What do you mean? self(new A()) ?
>>    
>>
>
>I mean, "let x be a reference to the method with type A -> A" and "let y be a
>reference to the method with type B -> B."
>  
>
OK, then there is no need for specific syntax. You could write anonymous 
functions (the eta-long form in lambda calculs) to disambiguate:

let x = A a => self(a);
let y = B b => self(b);

and x == y will be false. But comparing the identity of anonymous 
functions is not a very good idea in any case.

Daniel



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