Fwd: [tmql-wg] TMQL Issue: Functions and Predicates as first-class topics

[Lars Marius Garshol]

Sent this to the wrong list by mistake.

Begin forwarded message:

> From: Lars Marius Garshol <larsga at garshol.priv.no>
> Date: March 15, 2007 12:47:56 PM GMT+01:00
> To: Discussion of ISO/IEC 13250 Topic Maps <sc34wg3 at isotopicmaps.org>
> Subject: Re: [tmql-wg] TMQL Issue: Functions and Predicates as  
> first-class topics
>
>
> * Lars Heuer
>>
>> - The TM-ish style adds some syntactic noise to functions /  
>> predicates
>
> * Robert Barta
>>
>> I definitely buy that argument, that a 'dedicated' function syntax is
>> more dedicated than a generic TM syntax for functions. That is  
>> true by
>> definition, right? :-)
>
> This is the central point in the discussion, Robert. It would be  
> nice if you could take the counter-arguments seriously.
>
>> The downside of a specialized syntax is that - if we want to see  
>> these
>> things as topics, and the TM paradigm allows to do so anyway - it
>> takes ANOTHER, ADDITIONAL step to explain that. That step would  
>> fall away
>> if we would use a CTM syntax.
>
> Correct. However, so what? How important is this for people,  
> compared to ease of reading/writing of function/predicate  
> declarations? And how hard is it to explain, anyway? Let's see if I  
> can do it:
>
>   Each function becomes a topic of type tmql:function, with an  
> internal
>   occurrence tmql:return containing the query expression. The function
>   name becomes an item identifier for the topic.
>
> Doesn't look like it's much of a problem to explain.
>
>> What about allowing this in CTM:
>>
>>   person rho
>>      shoesize 43
>>
>> which is saying
>>
>>   rho isa person
>>   shoesize: 43
>
> I'll leave it to the other Lars to tell us whether that's workable  
> or not in CTM.
>
>> In this vein
>>
>>    tmql:def nr_employees
>>        tmql:return fn:length ( $o <- employer)
>>
>> or dropping the tmql: prefix
>>
>>    def nr_employees
>>        return fn:length ( $o <- employer)
>>
>> would also be a valid topic syntax.
>
> This looks a lot nicer. What about parameter declaration? What  
> about multi-line functions?
>
> --Lars M.

-- 
Lars Marius Garshol                         Mobile: +47 98 21 55 50
CTO, Ontopia                                Office: +47 23 23 30 83