Re: Object-relational impedence

Marshall wrote:

>On Mar 15, 4:49 pm, rp..._at_pcwin518.campus.tue.nl (rpost) wrote:
>> Marshall wrote:
>> >The "vague collections" idea is not a good one IMHO.
>> >Because you can get more or less everything you want
>> >with relations. (Surprise! I like relations! :-)
>>
>> But you often get more (e.g. you don't always need the
>> uniqueness of elements).
>
>There is really only one collection type where that is strictly
>true: bags. Bags seem to me to be the singularly least
>useful data structure I have encountered. Even so, they
>are acceptably encoded as relations over <element, count.>

Well, ordered lists are another, but they are only useful if no attribute can be modelled by which the ordering happens, and that is very rare; besides, they too can be expressed as relations, e.g. <element, nextelement> or <element, index>.

So I agree that not having them isn't so bad.

-- 
Reinier