The base-line functionality of Prolog implementations provides
indexing on constants and functor (name/arity) on the first argument.
This must be your assumption if wide portability of your program is
important. This can typically be achieved by exploiting term_hash/2
or term_hash/4
and/or maintaining multiple copies of a predicate with reordered
arguments and wrappers that update all implementations (assert/retract)
and selects the appropriate implementation (query).
YAP provides full JIT indexing, including indexing arguments of
compound terms. YAP's indexing has been the inspiration for enhancing
SWI-Prolog's indexing capabilities.
