prolog: Hyperscript bridge (+19)

pl-hs-query, pl-hs-predicate/1,2,3, pl-hs-install in hs-bridge.sx.
No parser/compiler changes: Hyperscript already compiles
`when allowed(user, action)` to (allowed user action).
Total 590/590.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/prolog/hs-bridge.sx

@@ -0,0 +1,72 @@
+;; lib/prolog/hs-bridge.sx — Prolog↔Hyperscript bridge
+;;
+;; Creates SX functions backed by a Prolog DB, callable directly from
+;; Hyperscript DSL conditions.  No parser/compiler changes needed:
+;;   when allowed(user, action) then …
+;; compiles to (allowed user action) — a plain SX call.
+;;
+;; Setup:
+;;   (define pl-db (pl-load "role(alice,admin). permission(admin,edit). allowed(U,A) :- role(U,R), permission(R,A)."))
+;;   (define allowed (pl-hs-predicate/2 pl-db "allowed"))
+;;
+;; Requires tokenizer.sx, parser.sx, runtime.sx, query.sx loaded first.
+
+;; Test whether a ground Prolog goal succeeds against db.
+;; Returns true/false (not a solution dict).
+(define
+  pl-hs-query
+  (fn (db goal-str) (not (nil? (pl-query-one db goal-str)))))
+
+;; Build a Prolog goal string from a predicate name and arg list.
+;; SX values: strings/keywords (already strings in SX) pass through;
+;; numbers are stringified via str.
+(define
+  pl-hs-build-goal
+  (fn
+    (pred-name args)
+    (str pred-name "(" (join ", " (map (fn (a) (str a)) args)) ")")))
+
+;; Return a 1-arg SX function that succeeds iff pred(a) holds in db.
+(define
+  pl-hs-predicate/1
+  (fn
+    (db pred-name)
+    (fn (a) (pl-hs-query db (pl-hs-build-goal pred-name (list a))))))
+
+;; Return a 2-arg SX function that succeeds iff pred(a, b) holds in db.
+(define
+  pl-hs-predicate/2
+  (fn
+    (db pred-name)
+    (fn (a b) (pl-hs-query db (pl-hs-build-goal pred-name (list a b))))))
+
+;; Return a 3-arg SX function that succeeds iff pred(a, b, c) holds in db.
+(define
+  pl-hs-predicate/3
+  (fn
+    (db pred-name)
+    (fn (a b c) (pl-hs-query db (pl-hs-build-goal pred-name (list a b c))))))
+
+;; Install every predicate in install-list as a named def in the caller's
+;; environment.  install-list: list of (name arity) pairs.
+;; Returns a dict {name → fn} for the caller to destructure.
+(define
+  pl-hs-install
+  (fn
+    (db install-list)
+    (reduce
+      (fn
+        (acc entry)
+        (let
+          ((pred-name (first entry)) (arity (nth entry 1)))
+          (dict-set!
+            acc
+            pred-name
+            (cond
+              ((= arity 1) (pl-hs-predicate/1 db pred-name))
+              ((= arity 2) (pl-hs-predicate/2 db pred-name))
+              ((= arity 3) (pl-hs-predicate/3 db pred-name))
+              (true (fn (a b) false))))
+          acc))
+      {}
+      install-list)))