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Re: list builtins done

From: Jos de Bruijn <debruijn@inf.unibz.it>
Date: Wed, 06 May 2009 17:07:29 +0200
Message-ID: <4A01A7B1.8050105@inf.unibz.it>
To: Chris Welty <cawelty@gmail.com>
CC: Sandro Hawke <sandro@w3.org>, public-rif-wg@w3.org
I can do this. Please assign me an action.


Jos

Chris Welty wrote:
> 
> So who will take up the issue of binding patterns for lists in Core? 
> Axel? Jos?
> 
> -Chris
> 
> Sandro Hawke wrote:
>> I think the DTB section on RIF lists [1] is now ready for review for
>> Last Call.  A few notes and questions:
>>
>>    * I removed the func:delete function, because           (a) it's
>> not in xpath,
>>           (b) it's confusingly similar to func:remove, and
>>           (c) it's trivial emulated:                  func:delete(L,
>> I) = func:except(L, func:make-list(I))
>>
>>      Some other functions are trivial emulated, but they're in xpath.  I
>>      think the bar is higher for us adding functions.  This way, the
>>      only ones we're adding are is-list, list-contains, make-list, and
>>      get.  list-contains is that only the can be emulated:
>>              list-contains(L, I) iff count(index-of(L, I)) > 0     
>> but I think we specifically discussed that and agreed it was
>>      worthwhile to have list-contains.
>>
>>      Obviously, if someone actually wants it, I'm okay with putting
>>      func:delete back in.
>>
>>    * This section has examples.  I could trivially suppress them for now
>>      (this wiki-text is generated by a program [2]), if they bother
>>      people.  I like them.  They have all been checked by my demo code
>>      [3].  I'm willing to make similar examples for the rest of DTB for
>>      a later edition.
>>
>>    * I don't know the right binding pattern for list-contains.  Above, I
>>      was assuming it was (b,b), but I can imagine some utility to all
>>      binding patterns, and at least (b,u) seems pretty reasonable.  It's
>>      not clear to me whether PR systems would do what I'm imagining with
>>      that, but it'd be nice to write rules like:
>>
>>          forall M (                   if  
>> list-contains(eg:list_of_friends, M)
>>            then eg:is_friend(M)
>>          )
>>
>>      Without it, I guess you'd need some much more cumbersome
>>      tail-recursive rules like this:
>>
>>          friend_list(eg:list_of_friends)              forall L M (
>>            if   friend_list(L) and
>>                 get(L, 0) = M
>>            then eg:is_friend(M)
>>          )
>>          forall L  (
>>            if   friend_list(L) and
>>                 count(L) > 0
>>            then friend_list(sublist(L, 1))
>>          )
>>
>>      PR folks, what do you want, there?
>>
>> I think that it.  This complete ACTION-760.
>>        -- Sandro
>>
>>
>> [1]
>> http://www.w3.org/2005/rules/wiki/DTB#Functions_and_Predicates_on_RIF_Lists
>>
>> [2] http://dev.w3.org/cvsweb/2009/rif/list_builtins.py
>>
>>
> 

-- 
+43 1 58801 18470        debruijn@inf.unibz.it

Jos de Bruijn,        http://www.debruijn.net/
----------------------------------------------
Many would be cowards if they had courage
enough.
  - Thomas Fuller


Received on Wednesday, 6 May 2009 15:15:15 GMT

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