Re: Ann: SWI-Prolog 7.1.0

Dear Jan, list,

On Sat, 7 Dec 2013 15:54:05 +0100
Jan Wielemaker <[email protected]> wrote:

> On 12/07/2013 02:48 PM, Michael Hendricks wrote:
> > Is there an efficient term_tag(+Term, -Tag:atom) predicate so we can
> > manually perform this optimization when wanted?
> > 
> > do(X) :-
> >     term_tag(X, Tag),
> >     do_(Tag, X).
> > do_(Tag, X) :-
> >     ...
> 
> Funny enough, this was also proposed by Nicos under the name
> term_type/2.  It might make sense, especially of a variable
> would leave the type unbound as well (just like term_hash/2).
> 
> Opinions?
> 
> 	Cheers --- Jan


	My point being  that now with the addition of strings we have a richer set,
        and that this is information that is cheap for the system to provide. 
	It will probably be hard to find a single definition to satisfy all.
	I suspect that it will be of limited usefulness, the application I have
	for them right now is in the context of a DSL.
        But where useful, they can be very handy. Not only you get efficiency, 
        but it also encourages more readable code. 
	My vote would be for the tightest type and a bound variable when arg(1) is variable. 
	Leaving Tag above unbound is counter intuitive (for my use case).

     
Thanks,

Nicos.