[kepler-dev] Question about OrderedRecordToken

[ben leinfelder]

Edward -
After some gumshoeing, I've found that, for me, the add operation does  
naturally order the labels in the result rather than preserving the  
given order of the ordered record tokens involved.
Then after some tinkering, I now have it locally so that:

'a.add(b)' returns a result in the order of 'a'
and
'b.add(a)' return a result in the order of 'b'

But that seems wrong because then the addition is not commutative.  
Perhaps we do need to enforce that the tokens have the same ordering  
(but I agree that also seems wrong).
-ben


On Dec 5, 2009, at 8:24 AM, Edward A. Lee wrote:

>
> One possibility would be to not perform the addition if
> the ordering is not the same.  This would be consistent
> with the fact that
>
>  [x = 1, y = 2] != [y = 2, x = 1]
>
> and that their types are different.
>
> I'm not sure about this though...
>
> Edward
>
>
> ben leinfelder wrote:
>> Edward,
>> I'm not sure what determines the order of the result when you add  
>> ordered record tokens - what do you suppose the order should be?  
>> With the example you have, I don't see a pattern. It's not even  
>> defaulting to the RecordToken ordering (alpha).
>> Does it make sense to have the result use the same ordering as the  
>> initial operand? Or should the operation fail when the tokens are  
>> not in the same order (seems severe)?
>> I'd expect
>> a.getType()
>> to return
>> object([x=int, y=int])
>> It seems to be deferring to the superclass for getType...something  
>> I should look into/fix.
>> Thanks for pointing these out.
>> -ben
>> On Dec 4, 2009, at 6:51 AM, Edward A. Lee wrote:
>>>
>>> Ben,
>>>
>>> I have a question about ordered record tokens.
>>> In the expression evaluator, I can do:
>>>
>>> >> a = [x = 1, y = 2]
>>> [x = 1, y = 2]
>>>
>>> >> c = [y = 2, x = 3]
>>> [y = 2, x = 3]
>>>
>>> >> a + c
>>> [y = 4, x = 4]
>>>
>>> >> c + a
>>> [y = 4, x = 4]
>>>
>>>
>>> What determines the order in the result?
>>>
>>> Also, if I do:
>>>
>>> >> a.getType()
>>> object({x = int, y = int})
>>>
>>> This description of the type seems exactly the same as
>>> the description I get from an (unordered) record token.
>>> Is this a problem? (I don't really know...)
>>>
>>> Thanks!
>>> Edward
>>> <eal.vcf>
> <eal.vcf>