🚀 go-pugleaf

In article <1992Apr9.004044.22425@athena.cs.uga.edu>, mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
> Prolog already uses hashing to look up facts and rules.  Hashing is
> applied to the predicate name itself (with arity) and (in most
> implementations) to the first argument of the predicate.

And in some Prologs, the hashing function is available to programmers,
so that complex terms can be hashed.  So, for example, you can do:

foo(X,Y,Z) :- hash_term(X-Y,Hash), foo2(Hash,X,Y,Z).

add_foo(X,Y,Z) :- hash_term(X-Y,Hash), assertz(foo2(Hash,X,Y,Z)).

Note that this depends on hash_term/2 returning a variable whenever
its first argument is not ground.

[If your Prolog implementation doesn't have hash_term/2, writing a C
function to implement it is a good test of how good the C interface is.]

-- 
	Peter Ludemann  +1-415-813-3800  ludemann@quintus.com