Comparing Multiple Values (the story so far/summary)

[Bill Baxter]

downs wrote:
> Bill Baxter wrote:
>> BCS wrote:
>>> Reply to Downs,
>>>
>>>> Bill Baxter wrote:
>>>>
>>>>> downs wrote:
>>>>>
>>>>>> `in` already is an infix operator :)
>>>>>>
>>>>>> --downs
>>>>>>
>>>>> Yes, but it doesn't work!
>>>>>
>>>>> --bb
>>>>>
>>>> Curious.
>>>>
>>>> Works here, GDC 1.028 / 4.1.2
>>>>
>>>> What are you using?
>>>>
>>>> --downs
>>>>
>>> I think he was saying the "in" operator dosn't work / works wrong. 
>> Right, as in "a in [1,2,3]"  is an error, rather than doing what the
>> poster who started this thread expected it to do.
>>
> 
> To give an example of W's stance ..
> 
> Say you have a book with four pages.
> 
> The first page contains the number 15, the second page 16 the third 23 and the fourth 42.
> 
> Now, if I ask "3 in book", do I mean "is the page 3 in the book" (index) or "is the number 3 in the book" (value)?
> 
> There's precedence in the D language for the first case, because `in` for AAs also checks against index (key) and not value.
> 
> However, checking against value would arguably be more useful :)
> 
> In the absence of a consensus, and because a case could be made for both possibilities, it was decided to leave it out for now.
> 
> That should about sum it up.

Yes, that sums it up quite nicely.

--bb