Re: [boost] any interest in Boost Unification and Backtracking library (UBL)?

From: Darren Cook (darren_at_[hidden])
Date: 2004-09-13 23:59:17

> =========== Is UBL feasible?===================
> 
> The short answer is yes. I already have the prototype up and running in VC++
> 7.1. The 8-queen problem takes less than 28 seconds on my Athlon 2200+ to
> find all answers.

How much does the plain prolog version take on the same hardware? I assume 
the motivation for using C++ is a speed-up?

And how many lines of code was the C++ version compared to the prolog one?

Is there a native C or C++ solution to the 8 queen problem for comparison?

> 2. syntax wise UBL predicates are not as straight-forward or visually
> appealing as the equivalent predicates in Prolog. 
[Example included at bottom]

I think you will have an uphill battle to persuade people to use the library 
because of this. Is a compiler or macro feasible to allow me to write the 
prolog one liner and have it turned into the C++ equivalent. (I don't use 
prolog but could understand and appreciate the prolog code example.)

Darren

Here is a predicate in
> UBL:
> 
> BOOST_UBL_PREDICATE_2_( is_grandfather_of, Person, Person )
> {
>     BOOST_UBL_VARIABLES_3
>  (
>   Person, X
>  , Person, Y
>  , Person, Z
>  );
> 
>     typedef clause< LHS<X, Y>
>             , is_father_of< X, Z >
>                 , is_father_of< Z, Y >
>   > type;
> };
> 
> Here is the equivalent predicates in Prolog:
> 
> is_grandfather_of(X, Y) :- is_father_of(X, Z), is_father_of( Z, Y).