artdag: Phase 2 Analyze on Datalog + 16 tests

analyze.sx projects DAG edges to (edge in out) facts and runs recursive
reachable rules for deps-of/dependents-of/reachable-from/ancestors-of, plus
dirty-closure (dirty(Y):-edge(X,Y),dirty(X)) for incremental recompute. Keystone:
changing a mid node dirties only it + downstream. analyze 16/16, total 36/36.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/artdag/analyze.sx

@@ -0,0 +1,88 @@
+; lib/artdag/analyze.sx — Phase 2: Analyze on Datalog.
+; Project the DAG's edges into a Datalog db and answer dependency questions
+; (deps, dependents, transitive reachability) plus dirty-closure propagation
+; as recursive Datalog — the acl/relations reachability shape. Depends on
+; lib/artdag/dag.sx and the lib/datalog/ public API.
+
+; edge(input-id, node-id): data flows input -> node (input is a dependency).
+(define
+  artdag/edge-facts
+  (fn
+    (dag)
+    (reduce
+      (fn
+        (acc id)
+        (concat
+          acc
+          (map
+            (fn (in) (list (quote edge) in id))
+            (artdag/node-inputs (artdag/dag-get dag id)))))
+      (list)
+      (keys (artdag/dag-nodes dag)))))
+
+; reachable(X,Y): Y is a transitive dependent of X (forward, downstream).
+(define
+  artdag/reach-rules
+  (quote
+    ((reachable X Y <- (edge X Y))
+      (reachable X Z <- (edge X Y) (reachable Y Z)))))
+
+(define
+  artdag/analyze
+  (fn (dag) (dl-program-data (artdag/edge-facts dag) artdag/reach-rules)))
+
+; pull a single variable's bindings out of a subst list, sorted for determinism.
+(define
+  artdag/-bindings
+  (fn
+    (substs var)
+    (artdag/sort-strings (map (fn (s) (get s var)) substs))))
+
+; direct dependencies (inputs) of a node.
+(define
+  artdag/deps-of
+  (fn
+    (db id)
+    (artdag/-bindings (dl-query db (list (quote edge) (quote X) id)) :X)))
+
+; direct dependents of a node.
+(define
+  artdag/dependents-of
+  (fn
+    (db id)
+    (artdag/-bindings (dl-query db (list (quote edge) id (quote Y))) :Y)))
+
+; transitive dependents (everything downstream of a node).
+(define
+  artdag/reachable-from
+  (fn
+    (db id)
+    (artdag/-bindings
+      (dl-query db (list (quote reachable) id (quote Y)))
+      :Y)))
+
+; transitive dependencies (everything upstream of a node).
+(define
+  artdag/ancestors-of
+  (fn
+    (db id)
+    (artdag/-bindings
+      (dl-query db (list (quote reachable) (quote X) id))
+      :X)))
+
+; dirty propagation: dirty(Y) :- edge(X,Y), dirty(X). Seeds are changed nodes.
+(define artdag/dirty-rules (quote ((dirty Y <- (edge X Y) (dirty X)))))
+
+(define
+  artdag/dirty-seeds
+  (fn (changed) (map (fn (c) (list (quote dirty) c)) changed)))
+
+; transitive dirty closure of a set of changed node-ids: the changed nodes plus
+; every transitive dependent that must recompute. Sorted, deduplicated.
+(define
+  artdag/dirty-closure
+  (fn
+    (dag changed)
+    (let
+      ((db (dl-program-data (concat (artdag/edge-facts dag) (artdag/dirty-seeds changed)) artdag/dirty-rules)))
+      (artdag/-bindings (dl-query db (list (quote dirty) (quote X))) :X))))

lib/artdag/conformance.sh

@@ -13,7 +13,7 @@ if [ ! -x "$SX_SERVER" ]; then
   exit 1
 fi
 
-SUITES=(dag)
+SUITES=(dag analyze)
 
 OUT_JSON="lib/artdag/scoreboard.json"
 OUT_MD="lib/artdag/scoreboard.md"
@@ -27,7 +27,17 @@ run_suite() {
 (epoch 1)
 (load "spec/stdlib.sx")
 (load "lib/r7rs.sx")
+(load "lib/datalog/tokenizer.sx")
+(load "lib/datalog/parser.sx")
+(load "lib/datalog/unify.sx")
+(load "lib/datalog/db.sx")
+(load "lib/datalog/builtins.sx")
+(load "lib/datalog/aggregates.sx")
+(load "lib/datalog/strata.sx")
+(load "lib/datalog/eval.sx")
+(load "lib/datalog/api.sx")
 (load "lib/artdag/dag.sx")
+(load "lib/artdag/analyze.sx")
 (epoch 2)
 (eval "(define artdag-test-pass 0)")
 (eval "(define artdag-test-fail 0)")

lib/artdag/scoreboard.json

@@ -1,8 +1,9 @@
 {
   "suites": {
-    "dag": {"pass": 20, "fail": 0}
+    "dag": {"pass": 20, "fail": 0},
+    "analyze": {"pass": 16, "fail": 0}
   },
-  "total_pass": 20,
+  "total_pass": 36,
   "total_fail": 0,
-  "total": 20
+  "total": 36
 }

lib/artdag/scoreboard.md

@@ -5,4 +5,5 @@ _Generated by `lib/artdag/conformance.sh`_
 | Suite | Pass | Fail | Total |
 |-------|-----:|-----:|------:|
 | dag | 20 | 0 | 20 |
-| **Total** | **20** | **0** | **20** |
+| analyze | 16 | 0 | 16 |
+| **Total** | **36** | **0** | **36** |

lib/artdag/tests/analyze.sx

@@ -0,0 +1,119 @@
+; Phase 2 — Analyze on Datalog: deps/dependents/reachability + dirty closure.
+
+; diamond:  a -> b, a -> c, (b,c) -> d
+(define
+  an-D
+  (artdag/build
+    (list
+      (list "a" "load" (list) {})
+      (list "b" "f" (list "a") {})
+      (list "c" "g" (list "a") {})
+      (list "d" "add" (list "b" "c") {} true))))
+(define an-db (artdag/analyze an-D))
+(define an-a (artdag/dag-id an-D "a"))
+(define an-b (artdag/dag-id an-D "b"))
+(define an-c (artdag/dag-id an-D "c"))
+(define an-d (artdag/dag-id an-D "d"))
+
+; ---- direct deps / dependents ----
+
+(artdag-test
+  "deps-of: direct inputs"
+  (artdag/deps-of an-db an-d)
+  (artdag/sort-strings (list an-b an-c)))
+
+(artdag-test "deps-of: leaf has none" (artdag/deps-of an-db an-a) (list))
+
+(artdag-test
+  "dependents-of: direct consumers"
+  (artdag/dependents-of an-db an-a)
+  (artdag/sort-strings (list an-b an-c)))
+
+(artdag-test
+  "dependents-of: output has none"
+  (artdag/dependents-of an-db an-d)
+  (list))
+
+; ---- transitive reachability ----
+
+(artdag-test
+  "reachable-from: all downstream"
+  (artdag/reachable-from an-db an-a)
+  (artdag/sort-strings (list an-b an-c an-d)))
+
+(artdag-test
+  "reachable-from: mid node reaches output"
+  (artdag/reachable-from an-db an-b)
+  (list an-d))
+
+(artdag-test
+  "ancestors-of: all upstream"
+  (artdag/ancestors-of an-db an-d)
+  (artdag/sort-strings (list an-a an-b an-c)))
+
+(artdag-test
+  "ancestors-of: leaf has none"
+  (artdag/ancestors-of an-db an-a)
+  (list))
+
+; ---- deep chain ----
+
+(define
+  ch-D
+  (artdag/build
+    (list
+      (list "a" "load" (list) {})
+      (list "b" "f" (list "a") {})
+      (list "c" "f" (list "b") {})
+      (list "d" "f" (list "c") {}))))
+(define ch-db (artdag/analyze ch-D))
+
+(artdag-test
+  "deep chain: reachable-from leaf"
+  (artdag/reachable-from ch-db (artdag/dag-id ch-D "a"))
+  (artdag/sort-strings
+    (list
+      (artdag/dag-id ch-D "b")
+      (artdag/dag-id ch-D "c")
+      (artdag/dag-id ch-D "d"))))
+
+(artdag-test
+  "deep chain: ancestors of tip"
+  (artdag/ancestors-of ch-db (artdag/dag-id ch-D "d"))
+  (artdag/sort-strings
+    (list
+      (artdag/dag-id ch-D "a")
+      (artdag/dag-id ch-D "b")
+      (artdag/dag-id ch-D "c"))))
+
+; ---- dirty closure ----
+
+(artdag-test
+  "dirty closure: change leaf dirties all"
+  (artdag/dirty-closure an-D (list an-a))
+  (artdag/sort-strings (list an-a an-b an-c an-d)))
+
+(artdag-test
+  "dirty closure: change mid touches only downstream"
+  (artdag/dirty-closure an-D (list an-b))
+  (artdag/sort-strings (list an-b an-d)))
+
+(artdag-test
+  "dirty closure: unaffected stay clean (count)"
+  (len (artdag/dirty-closure an-D (list an-b)))
+  2)
+
+(artdag-test
+  "dirty closure: change output dirties only itself"
+  (artdag/dirty-closure an-D (list an-d))
+  (list an-d))
+
+(artdag-test
+  "dirty closure: multiple seeds union"
+  (artdag/dirty-closure an-D (list an-b an-c))
+  (artdag/sort-strings (list an-b an-c an-d)))
+
+(artdag-test
+  "dirty closure: empty seed set"
+  (artdag/dirty-closure an-D (list))
+  (list))