Re: PIZZA time again :-)

dawn wrote:
>mAsterdam wrote:
>>>>Assume
>>>>1. there is a meaningful (or at least consequential)
>>>>difference between:
>>>>
>>>> toppings([salami, mozarella, onions]).
>>>> and
>>>> toppings([mozarella, onions, salami]).
[snip]
>>Consider
>>
>> merge(ListOfLists, MergedList).
>>
>>Now
>>
>>merge ([[salami, mozarella, onions][mozarella, onions, salami]], M).
>>
>>should fail because salami is before mozarella in the first list,
>>and after it in the second. It can't preserve the order.
>
> I don't know how you define a merge when there isn't
> an ordering defined on the type.
> Is there such a function? Your lists are ordered here,
> but your domain/type is not, unless you choose something
> like alpha order.

That is another way of asking the same question. What should 'merge' do when the order is not in the values (as it would be if we took the ordering defined on the type) but just in their position, relative to other values. It is what I'm trying to find out.

> I can imagine an interleave function that alternates ingredients from
> both lists and yields a pizza with salami on it twice (I think I'll
> pass on it, however). --dawn

So that is not the desired behaviour.
The resulting pizza will be richer than the originals, but I would like to see one you would like to eat.

>>Should
>>
>>merge([[salami, buttonmushroom, mozarella, onions][salami, artichoke,
>>mozarella]], M).
>>
>>succeed with
>> M = [salami, buttonmushroom, artichoke, mozarella, onions]
>> M = [salami, artichoke, buttonmushroom, mozarella, onions]
>>
>>or just the first one (because of the order of the lists)?
Received on Fri Sep 02 2005 - 21:32:22 CEST