The easiest way to call a predicate if you are only interested in
the first solution is to call the function SP_query(). It will
create a goal from the predicate definition and the
arguments, call it, and commit to the first solution found, if
any.
Returns SP_SUCCESS if the goal succeeded, SP_FAILURE
if it failed, and SP_ERROR if an error condition occurred. Only
when the return value is SP_SUCCESS are the values in the
query arguments valid, and will remain so until
backtracking into any enclosing query:
int SP_query(SP_pred_ref predicate, SP_term_ref arg1, ...)
If you are only interested in the side-effects of a
predicate you can call SP_query_cut_fail(). It will try to
prove the predicate, cut away the rest of the solutions, and
finally fail. This will reclaim the storage used after the call, and
throw away any solution found. The return values are the same as for
SP_query().
int SP_query_cut_fail(SP_pred_ref predicate, SP_term_ref arg1, ...)