datalog: findall aggregate (159/159)

(findall L V Goal) — bind L to the distinct V values for which Goal
holds, or the empty list when none. One-line addition to
dl-do-aggregate that returns the unreduced list. Tests cover EDB,
derived relation, and empty cases.

Useful for "give me all the X such that ..." queries without
scalar reduction.

lib/datalog/aggregates.sx

@@ -19,7 +19,7 @@
 ;;
 ;; Empty input: count → 0, sum → 0, min/max → no binding (rule fails).
 
-(define dl-aggregate-rels (list "count" "sum" "min" "max"))
+(define dl-aggregate-rels (list "count" "sum" "min" "max" "findall"))
 
 (define
   dl-aggregate?
@@ -43,6 +43,7 @@
     (cond
       ((= op "count") (len vals))
       ((= op "sum") (dl-sum-vals vals 0))
+      ((= op "findall") vals)
       ((= op "min")
         (cond
           ((= (len vals) 0) :empty)

lib/datalog/scoreboard.json

@@ -1,8 +1,8 @@
 {
   "lang": "datalog",
-  "total_passed": 156,
+  "total_passed": 159,
   "total_failed": 0,
-  "total": 156,
+  "total": 159,
   "suites": [
     {"name":"tokenize","passed":26,"failed":0,"total":26},
     {"name":"parse","passed":18,"failed":0,"total":18},
@@ -11,9 +11,9 @@
     {"name":"builtins","passed":19,"failed":0,"total":19},
     {"name":"semi_naive","passed":8,"failed":0,"total":8},
     {"name":"negation","passed":10,"failed":0,"total":10},
-    {"name":"aggregates","passed":10,"failed":0,"total":10},
+    {"name":"aggregates","passed":13,"failed":0,"total":13},
     {"name":"api","passed":9,"failed":0,"total":9},
     {"name":"demo","passed":10,"failed":0,"total":10}
   ],
-  "generated": "2026-05-08T08:57:57+00:00"
+  "generated": "2026-05-08T09:02:31+00:00"
 }

lib/datalog/scoreboard.md

@@ -1,6 +1,6 @@
 # datalog scoreboard
 
-**156 / 156 passing** (0 failure(s)).
+**159 / 159 passing** (0 failure(s)).
 
 | Suite | Passed | Total | Status |
 |-------|--------|-------|--------|
@@ -11,6 +11,6 @@
 | builtins | 19 | 19 | ok |
 | semi_naive | 8 | 8 | ok |
 | negation | 10 | 10 | ok |
-| aggregates | 10 | 10 | ok |
+| aggregates | 13 | 13 | ok |
 | api | 9 | 9 | ok |
 | demo | 10 | 10 | ok |

lib/datalog/tests/aggregates.sx

@@ -199,6 +199,33 @@
           (list (quote popular) (quote P)))
         (list {:P (quote p1)}))
 
+      ;; findall: collect distinct values into a list.
+      (dl-at-test-set! "findall over EDB"
+        (dl-query
+          (dl-program
+            "p(a). p(b). p(c).
+             all_p(L) :- findall(L, X, p(X)).")
+          (list (quote all_p) (quote L)))
+        (list {:L (list (quote a) (quote b) (quote c))}))
+
+      (dl-at-test-set! "findall over derived"
+        (dl-query
+          (dl-program
+            "parent(a, b). parent(b, c). parent(c, d).
+             ancestor(X, Y) :- parent(X, Y).
+             ancestor(X, Z) :- parent(X, Y), ancestor(Y, Z).
+             desc(L) :- findall(L, X, ancestor(a, X)).")
+          (list (quote desc) (quote L)))
+        (list {:L (list (quote b) (quote c) (quote d))}))
+
+      (dl-at-test-set! "findall empty"
+        (dl-query
+          (dl-program
+            "p(1).
+             all_q(L) :- findall(L, X, q(X)).")
+          (list (quote all_q) (quote L)))
+        (list {:L (list)}))
+
       ;; Aggregate vs single distinct.
       (dl-at-test-set! "distinct counted once"
         (dl-query

plans/datalog-on-sx.md

@@ -186,9 +186,10 @@ large graphs.
 
 ### Phase 8 — aggregation (Datalog+)
 - [x] `(count R V Goal)`, `(sum R V Goal)`, `(min R V Goal)`,
-      `(max R V Goal)` — first arg is the result variable, second is the
-      aggregated variable, third is the goal literal. Live in
-      `lib/datalog/aggregates.sx`.
+      `(max R V Goal)`, `(findall L V Goal)` — first arg is the result
+      variable, second is the aggregated variable, third is the goal
+      literal. `findall` returns the distinct-value list itself; the
+      others reduce. Live in `lib/datalog/aggregates.sx`.
 - [x] `dl-eval-aggregate`: runs `dl-find-bindings` on the goal under the
       current subst (which provides outer-context bindings), collects
       distinct values of the aggregated var, applies the aggregate.
@@ -269,6 +270,13 @@ large graphs.
 
 _Newest first._
 
+- 2026-05-08 — Phase 8 extension: `findall L V Goal` aggregate. Bind
+  L to the list of distinct V values for which Goal holds (or the
+  empty list when no matches). Implemented as a one-line case in
+  `dl-do-aggregate`. 3 new tests: EDB, derived relation, empty.
+  Useful for "give me all the X such that …" queries without
+  scalar reduction.
+
 - 2026-05-08 — Phase 5d semantic fix: anonymous `_` variables are
   renamed per occurrence at `dl-add-rule!` and `dl-query` time so
   `(p X _) (p _ Y)` no longer unifies the two `_`s. New helpers