Re: ISSUE-92: n-ary builtins

My preference here would be (3) below.
If not that then we could drop the fixed arity requirement for externals.
I don't see it as a change that will require us to redo the LC.

michael

On Fri, 27 Feb 2009 15:32:42 -0500
Chris Welty <cawelty@gmail.com> wrote:

> 
> The basic issue is that BLD (and core) require all predicates and functions to 
> have a fixed arity, but in DTB we reuse many xpath/xquery functions and 
> predicates, and there are several that do not have a fixed arity (e.g. concat). 
>       In DTB, the treatment of these operators is unclear:
> 
> "numbering the different versions of the respective built-ins and treating the 
> unnumbered version as syntactic sugar, i.e. for instance instead of External( 
> func:concat2( str1, str2) ) and External( func:concat3( str1 str2 str3 ) ) we 
> allow the equivalent forms External( func:concat( str1, str2) ) and External( 
> func:concat( str1 str2 str3 ) )."
> 
> Does this mean that BLD should allow rulesets to use concat with any arity, or 
> does it mean that for the purposes of DTB we write concat as a shortcut for 
> whichever (concat2, concat3, etc) is appropriate?
> 
> Possible solutions:
> 
> 1) Make it clear this is only for the purposes of writing DTB, and that all 
> rulesets must use a fixed arity function/predicate
> 
> 2) Allow for some preprocessing step in RIF implementations where functions like 
> concat are replaced with their fixed-arity equivalents
> 
> 3) Change BLD to allow for arbitrary arity functions and predicates. I can find 
> no formal resolution to make preds/funs fixed arity, however it would be a major 
> change to a LC document (BLD).  At the last telecon, no one was opposed to this 
> change on technical grounds, only because of the LC status.
> 
> </chair>
> I prefer option 1.
> <chair>
> 
> 
>

Received on Friday, 27 February 2009 21:41:02 UTC