Single-call entry: dl-eval source-string query-string parses
both, builds a db via dl-program, saturates implicitly, runs
the query (extracted from the parsed `?- ...` clause), and
returns the substitution list.
Most user-friendly path:
(dl-eval "parent(a, b). ..." "?- ancestor(a, X).")
2 new api tests cover ancestor and multi-goal usage.
db gains :facts-index {<rel>: {<first-arg-key>: tuples}} mirroring
the membership :facts-keys index. dl-add-fact! populates the index;
dl-match-positive walks the body literal's first arg under the
current subst — when it's bound to a non-var, look up by (str arg)
instead of scanning the full relation.
For chain-style recursive rules (parent X Y), (ancestor Y Z) the
inner Y has at most one parent, so the inner lookup returns 0–1
tuples instead of N. chain-25 saturation drops from ~33s to ~18s
real (~2x). chain-50 still long but tractable; next bottleneck is
subst dict copies during unification.
dl-retract! refreshed to keep the new index consistent: kept-index
rebuilt during EDB filter, IDB wipes clear all three slots.
Differential semi-naive test bumped to chain-12, semi-only count
test to chain-25.
db gains a parallel :facts-keys {<rel>: {<tuple-string>: true}}
index alongside :facts. dl-tuple-key derives a stable string via
(str lit) — (p 30) and (p 30.0) collide correctly because SX
prints them identically. dl-add-fact! membership is now O(1)
instead of O(n) list scan; insert sequences for relations sized
N drop from O(N²) to O(N).
Wall clock on chain-7 saturation halves (~12s → ~6s); chain-15
roughly halves (~50s → ~25s) under shared CPU. Larger chains
still slow due to body-join overhead in dl-find-bindings —
Blocker entry refreshed with proposed follow-ups.
dl-retract! keeps both indices consistent: kept-keys is rebuilt
during the EDB filter, IDB wipes clear both lists and key dicts.
New lib/datalog/api.sx: dl-program-data facts rules takes SX data
lists. Rules accept either dict form or list form using <- as the
rule arrow (since SX parses :- as a keyword). dl-rule constructor
for the dict shape. dl-assert! adds a fact and re-saturates;
dl-retract! drops EDB matches, wipes all rule-headed IDB
relations, and re-saturates from scratch — simplest correct
semantics until provenance tracking arrives.
9 API tests cover ancestor closure via data, dict-rule form,
dl-rule constructor, incremental assert/retract, cyclic-graph
reach, assert into empty, fact-style rule (no arrow), dict
passthrough.
