GUEST: step 4 — lib/guest/pratt.sx operator-table format + lookup

Extracted the data-half of Pratt-style precedence parsing: the operator
table format and lookup. The climbing loop stays per-language because
the two canaries use opposite conventions (lua: higher prec = tighter;
prolog: lower prec = tighter, with xfx/xfy/yfx assoc tags) — forcing
one shared loop adds callback indirection that obscures more than it
shares. The brief's literal ask is "Grammar is a dict, not hardcoded
cond" and that's what gets shared.

Entry shape: (NAME PREC ASSOC). Three accessors: pratt-op-name /
pratt-op-prec / pratt-op-assoc. One traversal: pratt-op-lookup.

Ported lua/parser.sx — replaced 18-clause cond and the
lua-binop-right? hardcoded `or` with a 15-entry lua-op-table, now
queried via pratt-op-lookup. Ported prolog/parser.sx — pl-op-find
(linear walk reimpl) deleted; pl-op-lookup wraps pratt-op-lookup;
pl-token-op simplified to return the entry directly.

Verification:
- lua/test.sh: 185/185 = baseline.
- prolog/conformance.sh: 590/590 = baseline (timestamp-only diff).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/lua/parser.sx

@@ -3,28 +3,33 @@
 (define lua-tok-value (fn (t) (if (= t nil) nil (get t :value))))
 
 (define
-  lua-binop-prec
-  (fn
-    (op)
-    (cond
-      ((= op "or") 1)
-      ((= op "and") 2)
-      ((= op "<") 3)
-      ((= op ">") 3)
-      ((= op "<=") 3)
-      ((= op ">=") 3)
-      ((= op "==") 3)
-      ((= op "~=") 3)
-      ((= op "..") 5)
-      ((= op "+") 6)
-      ((= op "-") 6)
-      ((= op "*") 7)
-      ((= op "/") 7)
-      ((= op "%") 7)
-      ((= op "^") 10)
-      (else 0))))
+  lua-op-table
+  (list
+    (list "or"  1 :left)
+    (list "and" 2 :left)
+    (list "<"   3 :left)
+    (list ">"   3 :left)
+    (list "<="  3 :left)
+    (list ">="  3 :left)
+    (list "=="  3 :left)
+    (list "~="  3 :left)
+    (list ".."  5 :right)
+    (list "+"   6 :left)
+    (list "-"   6 :left)
+    (list "*"   7 :left)
+    (list "/"   7 :left)
+    (list "%"   7 :left)
+    (list "^"  10 :right)))
 
-(define lua-binop-right? (fn (op) (or (= op "..") (= op "^"))))
+(define lua-binop-prec
+  (fn (op)
+    (let ((entry (pratt-op-lookup lua-op-table op)))
+      (if (= entry nil) 0 (pratt-op-prec entry)))))
+
+(define lua-binop-right?
+  (fn (op)
+    (let ((entry (pratt-op-lookup lua-op-table op)))
+      (and (not (= entry nil)) (= (pratt-op-assoc entry) :right)))))
 
 (define
   lua-parse

lib/lua/test.sh

@@ -30,6 +30,7 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 1)
 (load "lib/guest/lex.sx")
 (load "lib/guest/prefix.sx")
+(load "lib/guest/pratt.sx")
 (load "lib/lua/tokenizer.sx")
 (epoch 2)
 (load "lib/lua/parser.sx")