From 8a9c07414120e92a2d1785680810cf3c22259eea Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Sat, 25 Apr 2026 18:08:27 +0000
Subject: [PATCH] prolog: compile clauses to SX closures (+17)

---
 lib/prolog/compiler.sx       | 157 +++++++++++++++++++++++++++++
 lib/prolog/conformance.sh    |   4 +-
 lib/prolog/runtime.sx        |  31 ++++--
 lib/prolog/tests/compiler.sx | 185 +++++++++++++++++++++++++++++++++++
 4 files changed, 367 insertions(+), 10 deletions(-)
 create mode 100644 lib/prolog/compiler.sx
 create mode 100644 lib/prolog/tests/compiler.sx

diff --git a/lib/prolog/compiler.sx b/lib/prolog/compiler.sx
new file mode 100644
index 00000000..c3c80a5f
--- /dev/null
+++ b/lib/prolog/compiler.sx
@@ -0,0 +1,157 @@
+;; lib/prolog/compiler.sx — clause compiler: parse-AST clauses → SX closures
+;;
+;; Each compiled clause is a lambda (fn (goal trail db cut-box k) bool)
+;; that creates fresh vars, builds the instantiated head/body, and calls
+;; pl-unify! + pl-solve! directly — no AST walk at solve time.
+;;
+;; Usage:
+;;   (pl-db-load! db (pl-parse src))
+;;   (pl-compile-db! db)
+;;   ; pl-solve-user! in runtime.sx automatically prefers compiled clauses
+;;   (pl-solve-once! db goal trail)
+
+;; Collect unique variable names from a parse-AST clause into a dict.
+(define
+  pl-cmp-vars-into!
+  (fn
+    (ast seen)
+    (cond
+      ((not (list? ast)) nil)
+      ((empty? ast) nil)
+      ((= (first ast) "var")
+        (let
+          ((name (nth ast 1)))
+          (when
+            (and (not (= name "_")) (not (dict-has? seen name)))
+            (dict-set! seen name true))))
+      ((= (first ast) "compound")
+        (for-each (fn (a) (pl-cmp-vars-into! a seen)) (nth ast 2)))
+      ((= (first ast) "clause")
+        (begin
+          (pl-cmp-vars-into! (nth ast 1) seen)
+          (pl-cmp-vars-into! (nth ast 2) seen))))))
+
+;; Return list of unique var names in a clause (head + body, excluding _).
+(define
+  pl-cmp-collect-vars
+  (fn
+    (clause)
+    (let ((seen {})) (pl-cmp-vars-into! clause seen) (keys seen))))
+
+;; Create a fresh runtime var for each name in the list; return name->var dict.
+(define
+  pl-cmp-make-var-map
+  (fn
+    (var-names)
+    (let
+      ((m {}))
+      (for-each
+        (fn (name) (dict-set! m name (pl-mk-rt-var name)))
+        var-names)
+      m)))
+
+;; Instantiate a parse-AST term using a pre-built var-map.
+;; ("var" "_") always gets a fresh anonymous var.
+(define
+  pl-cmp-build-term
+  (fn
+    (ast var-map)
+    (cond
+      ((pl-var? ast) ast)
+      ((not (list? ast)) ast)
+      ((empty? ast) ast)
+      ((= (first ast) "var")
+        (let
+          ((name (nth ast 1)))
+          (if (= name "_") (pl-mk-rt-var "_") (dict-get var-map name))))
+      ((or (= (first ast) "atom") (= (first ast) "num") (= (first ast) "str"))
+        ast)
+      ((= (first ast) "compound")
+        (list
+          "compound"
+          (nth ast 1)
+          (map (fn (a) (pl-cmp-build-term a var-map)) (nth ast 2))))
+      ((= (first ast) "clause")
+        (list
+          "clause"
+          (pl-cmp-build-term (nth ast 1) var-map)
+          (pl-cmp-build-term (nth ast 2) var-map)))
+      (true ast))))
+
+;; Compile one parse-AST clause to a lambda.
+;; Pre-computes var names at compile time; creates fresh vars per call.
+(define
+  pl-compile-clause
+  (fn
+    (clause)
+    (let
+      ((var-names (pl-cmp-collect-vars clause))
+        (head-ast (nth clause 1))
+        (body-ast (nth clause 2)))
+      (fn
+        (goal trail db cut-box k)
+        (let
+          ((var-map (pl-cmp-make-var-map var-names)))
+          (let
+            ((fresh-head (pl-cmp-build-term head-ast var-map))
+              (fresh-body (pl-cmp-build-term body-ast var-map)))
+            (let
+              ((mark (pl-trail-mark trail)))
+              (if
+                (pl-unify! goal fresh-head trail)
+                (let
+                  ((r (pl-solve! db fresh-body trail cut-box k)))
+                  (if r true (begin (pl-trail-undo-to! trail mark) false)))
+                (begin (pl-trail-undo-to! trail mark) false)))))))))
+
+;; Try a list of compiled clause lambdas — same cut semantics as pl-try-clauses!.
+(define
+  pl-try-compiled-clauses!
+  (fn
+    (db
+      goal
+      trail
+      compiled-clauses
+      outer-cut-box
+      outer-was-cut
+      inner-cut-box
+      k)
+    (cond
+      ((empty? compiled-clauses) false)
+      (true
+        (let
+          ((r ((first compiled-clauses) goal trail db inner-cut-box k)))
+          (cond
+            (r true)
+            ((dict-get inner-cut-box :cut) false)
+            ((and (not outer-was-cut) (dict-get outer-cut-box :cut)) false)
+            (true
+              (pl-try-compiled-clauses!
+                db
+                goal
+                trail
+                (rest compiled-clauses)
+                outer-cut-box
+                outer-was-cut
+                inner-cut-box
+                k))))))))
+
+;; Compile all clauses in DB and store in :compiled table.
+;; After this call, pl-solve-user! will dispatch via compiled lambdas.
+;; Note: clauses assert!-ed after this call are not compiled.
+(define
+  pl-compile-db!
+  (fn
+    (db)
+    (let
+      ((src-table (dict-get db :clauses)) (compiled-table {}))
+      (for-each
+        (fn
+          (key)
+          (dict-set!
+            compiled-table
+            key
+            (map pl-compile-clause (dict-get src-table key))))
+        (keys src-table))
+      (dict-set! db :compiled compiled-table)
+      db)))
diff --git a/lib/prolog/conformance.sh b/lib/prolog/conformance.sh
index 4f840cf9..da9da278 100755
--- a/lib/prolog/conformance.sh
+++ b/lib/prolog/conformance.sh
@@ -41,13 +41,15 @@ SUITES=(
   "assert_rules:lib/prolog/tests/assert_rules.sx:pl-assert-rules-tests-run!"
   "string_agg:lib/prolog/tests/string_agg.sx:pl-string-agg-tests-run!"
   "advanced:lib/prolog/tests/advanced.sx:pl-advanced-tests-run!"
+  "compiler:lib/prolog/tests/compiler.sx:pl-compiler-tests-run!"
 )
 
 SCRIPT='(epoch 1)
 (load "lib/prolog/tokenizer.sx")
 (load "lib/prolog/parser.sx")
 (load "lib/prolog/runtime.sx")
-(load "lib/prolog/query.sx")'
+(load "lib/prolog/query.sx")
+(load "lib/prolog/compiler.sx")'
 for entry in "${SUITES[@]}"; do
   IFS=: read -r _ file _ <<< "$entry"
   SCRIPT+=$'\n(load "'"$file"$'")'
diff --git a/lib/prolog/runtime.sx b/lib/prolog/runtime.sx
index f9a1342f..257894a0 100644
--- a/lib/prolog/runtime.sx
+++ b/lib/prolog/runtime.sx
@@ -2704,15 +2704,28 @@
       ((inner-cut-box {:cut false}))
       (let
         ((outer-was-cut (dict-get outer-cut-box :cut)))
-        (pl-try-clauses!
-          db
-          goal
-          trail
-          (pl-db-lookup-goal db goal)
-          outer-cut-box
-          outer-was-cut
-          inner-cut-box
-          k)))))
+        (let
+          ((compiled (when (dict-has? db :compiled) (dict-get db :compiled))))
+          (if
+            (and compiled (dict-has? compiled (pl-goal-key goal)))
+            (pl-try-compiled-clauses!
+              db
+              goal
+              trail
+              (dict-get compiled (pl-goal-key goal))
+              outer-cut-box
+              outer-was-cut
+              inner-cut-box
+              k)
+            (pl-try-clauses!
+              db
+              goal
+              trail
+              (pl-db-lookup-goal db goal)
+              outer-cut-box
+              outer-was-cut
+              inner-cut-box
+              k)))))))
 
 (define
   pl-try-clauses!
diff --git a/lib/prolog/tests/compiler.sx b/lib/prolog/tests/compiler.sx
new file mode 100644
index 00000000..cf85dd29
--- /dev/null
+++ b/lib/prolog/tests/compiler.sx
@@ -0,0 +1,185 @@
+;; lib/prolog/tests/compiler.sx — compiled clause dispatch tests
+
+(define pl-cmp-test-count 0)
+(define pl-cmp-test-pass 0)
+(define pl-cmp-test-fail 0)
+(define pl-cmp-test-failures (list))
+
+(define
+  pl-cmp-test!
+  (fn
+    (name got expected)
+    (set! pl-cmp-test-count (+ pl-cmp-test-count 1))
+    (if
+      (= got expected)
+      (set! pl-cmp-test-pass (+ pl-cmp-test-pass 1))
+      (begin
+        (set! pl-cmp-test-fail (+ pl-cmp-test-fail 1))
+        (append! pl-cmp-test-failures name)))))
+
+;; Load src, compile, return DB.
+(define
+  pl-cmp-mk
+  (fn
+    (src)
+    (let
+      ((db (pl-mk-db)))
+      (pl-db-load! db (pl-parse src))
+      (pl-compile-db! db)
+      db)))
+
+;; Run goal string against compiled DB; return bool (instantiates vars).
+(define
+  pl-cmp-once
+  (fn
+    (db src)
+    (pl-solve-once!
+      db
+      (pl-instantiate (pl-parse-goal src) {})
+      (pl-mk-trail))))
+
+;; Count solutions for goal string against compiled DB.
+(define
+  pl-cmp-count
+  (fn
+    (db src)
+    (pl-solve-count!
+      db
+      (pl-instantiate (pl-parse-goal src) {})
+      (pl-mk-trail))))
+
+;; ── 1. Simple facts ──────────────────────────────────────────────
+
+(define pl-cmp-db1 (pl-cmp-mk "color(red). color(green). color(blue)."))
+
+(pl-cmp-test! "compiled fact hit" (pl-cmp-once pl-cmp-db1 "color(red)") true)
+(pl-cmp-test!
+  "compiled fact miss"
+  (pl-cmp-once pl-cmp-db1 "color(yellow)")
+  false)
+(pl-cmp-test! "compiled fact count" (pl-cmp-count pl-cmp-db1 "color(X)") 3)
+
+;; ── 2. Recursive rule: append ────────────────────────────────────
+
+(define
+  pl-cmp-db2
+  (pl-cmp-mk "append([], L, L). append([H|T], L, [H|R]) :- append(T, L, R)."))
+
+(pl-cmp-test!
+  "compiled append build"
+  (pl-cmp-once pl-cmp-db2 "append([1,2],[3],[1,2,3])")
+  true)
+(pl-cmp-test!
+  "compiled append fail"
+  (pl-cmp-once pl-cmp-db2 "append([1,2],[3],[1,2])")
+  false)
+(pl-cmp-test!
+  "compiled append split count"
+  (pl-cmp-count pl-cmp-db2 "append(X, Y, [a,b])")
+  3)
+
+;; ── 3. Cut ───────────────────────────────────────────────────────
+
+(define
+  pl-cmp-db3
+  (pl-cmp-mk "first(X, [X|_]) :- !. first(X, [_|T]) :- first(X, T)."))
+
+(pl-cmp-test!
+  "compiled cut: only one solution"
+  (pl-cmp-count pl-cmp-db3 "first(X, [a,b,c])")
+  1)
+
+(let
+  ((db pl-cmp-db3) (trail (pl-mk-trail)) (env {}))
+  (let
+    ((x (pl-mk-rt-var "X")))
+    (dict-set! env "X" x)
+    (pl-solve-once!
+      db
+      (pl-instantiate (pl-parse-goal "first(X, [a,b,c])") env)
+      trail)
+    (pl-cmp-test!
+      "compiled cut: correct binding"
+      (pl-atom-name (pl-walk x))
+      "a")))
+
+;; ── 4. member ────────────────────────────────────────────────────
+
+(define
+  pl-cmp-db4
+  (pl-cmp-mk "member(X, [X|_]). member(X, [_|T]) :- member(X, T)."))
+
+(pl-cmp-test!
+  "compiled member hit"
+  (pl-cmp-once pl-cmp-db4 "member(b, [a,b,c])")
+  true)
+(pl-cmp-test!
+  "compiled member miss"
+  (pl-cmp-once pl-cmp-db4 "member(d, [a,b,c])")
+  false)
+(pl-cmp-test!
+  "compiled member count"
+  (pl-cmp-count pl-cmp-db4 "member(X, [a,b,c])")
+  3)
+
+;; ── 5. Arithmetic in body ────────────────────────────────────────
+
+(define pl-cmp-db5 (pl-cmp-mk "double(X, Y) :- Y is X * 2."))
+
+(let
+  ((db pl-cmp-db5) (trail (pl-mk-trail)) (env {}))
+  (let
+    ((y (pl-mk-rt-var "Y")))
+    (dict-set! env "Y" y)
+    (pl-solve-once!
+      db
+      (pl-instantiate (pl-parse-goal "double(5, Y)") env)
+      trail)
+    (pl-cmp-test! "compiled arithmetic in body" (pl-num-val (pl-walk y)) 10)))
+
+;; ── 6. Transitive ancestor ───────────────────────────────────────
+
+(define
+  pl-cmp-db6
+  (pl-cmp-mk
+    (str
+      "parent(a,b). parent(b,c). parent(c,d)."
+      "ancestor(X,Y) :- parent(X,Y)."
+      "ancestor(X,Y) :- parent(X,Z), ancestor(Z,Y).")))
+
+(pl-cmp-test!
+  "compiled ancestor direct"
+  (pl-cmp-once pl-cmp-db6 "ancestor(a,b)")
+  true)
+(pl-cmp-test!
+  "compiled ancestor 3-step"
+  (pl-cmp-once pl-cmp-db6 "ancestor(a,d)")
+  true)
+(pl-cmp-test!
+  "compiled ancestor fail"
+  (pl-cmp-once pl-cmp-db6 "ancestor(d,a)")
+  false)
+
+;; ── 7. Fallback: uncompiled predicate calls compiled sub-predicate
+
+(define
+  pl-cmp-db7
+  (let
+    ((db (pl-mk-db)))
+    (pl-db-load! db (pl-parse "q(1). q(2)."))
+    (pl-compile-db! db)
+    (pl-db-load! db (pl-parse "r(X) :- q(X)."))
+    db))
+
+(pl-cmp-test!
+  "uncompiled predicate resolves"
+  (pl-cmp-once pl-cmp-db7 "r(1)")
+  true)
+(pl-cmp-test!
+  "uncompiled calls compiled sub-pred count"
+  (pl-cmp-count pl-cmp-db7 "r(X)")
+  2)
+
+;; ── Runner ───────────────────────────────────────────────────────
+
+(define pl-compiler-tests-run! (fn () {:failed pl-cmp-test-fail :passed pl-cmp-test-pass :total pl-cmp-test-count :failures pl-cmp-test-failures}))