js-on-sx: globalThis + eval stub transpile-time mappings

JS 'globalThis' now rewrites to SX (js-global) — the global object dict.
JS 'eval' rewrites to js-global-eval, a no-op stub that echoes its first
arg. Many test262 tests probe eval's existence or pass simple literals
through it; a no-op is better than 'Undefined symbol: eval'.

A full eval would require plumbing js-eval into the runtime with access
to the enclosing lexical scope — non-trivial. The stub unblocks tests
that just need eval to be callable.

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

lib/js/runtime.sx

@@ -23,6 +23,12 @@
 
 ;; ── Boolean coercion (ToBoolean) ──────────────────────────────────
 
+(define
+  js-global-eval
+  (fn (&rest args) (if (empty? args) :js-undefined (nth args 0))))
+
+;; ── Numeric coercion (ToNumber) ───────────────────────────────────
+
 (define
   js-max-value-loop
   (fn
@@ -37,22 +43,20 @@
           cur
           (js-max-value-loop next (- steps 1)))))))
 
-;; ── Numeric coercion (ToNumber) ───────────────────────────────────
-
-(define js-undefined :js-undefined)
-
 ;; Parse a JS-style string to a number. For the slice we just delegate
 ;; to SX's number parser via `str->num`/`parse-number`. Empty string → 0
 ;; per JS (technically ToNumber("") === 0).
-(define js-undefined? (fn (v) (= v :js-undefined)))
+(define js-undefined :js-undefined)
 
 ;; Safe number-parser. Tries to call an SX primitive that can parse
 ;; strings to numbers; on failure returns 0 (stand-in for NaN so the
 ;; slice doesn't crash).
-(define __js_this_cell__ (dict))
+(define js-undefined? (fn (v) (= v :js-undefined)))
 
 ;; Minimal string->number for the slice. Handles integers, negatives,
 ;; and simple decimals. Returns 0 on malformed input.
+(define __js_this_cell__ (dict))
+
 (define
   js-this
   (fn
@@ -116,6 +120,13 @@
             0
             (+ 1 (js-count-real-params (rest params)))))))))
 
+;; parse a decimal number from a trimmed non-empty string.
+;;   s      — source
+;;   i      — cursor
+;;   acc    — integer part so far (or total for decimals)
+;;   sign   — 1 or -1
+;;   frac?  — are we past the decimal point
+;;   fdiv   — divisor used to scale fraction digits (only if frac?)
 (define
   js-invoke-function-method
   (fn
@@ -153,13 +164,6 @@
       ((= key "length") (js-fn-length recv))
       (else :js-undefined))))
 
-;; parse a decimal number from a trimmed non-empty string.
-;;   s      — source
-;;   i      — cursor
-;;   acc    — integer part so far (or total for decimals)
-;;   sign   — 1 or -1
-;;   frac?  — are we past the decimal point
-;;   fdiv   — divisor used to scale fraction digits (only if frac?)
 (define
   js-invoke-function-bound
   (fn
@@ -202,6 +206,8 @@
             (js-to-string key)
             " is not a function (on number)"))))))
 
+;; ── String coercion (ToString) ────────────────────────────────────
+
 (define
   js-invoke-function-objproto
   (fn
@@ -218,8 +224,6 @@
       ((= key "toLocaleString") "function () { [native code] }")
       (else :js-undefined))))
 
-;; ── String coercion (ToString) ────────────────────────────────────
-
 (define
   js-invoke-boolean-method
   (fn
@@ -234,6 +238,9 @@
             (js-to-string key)
             " is not a function (on boolean)"))))))
 
+;; ── Arithmetic (JS rules) ─────────────────────────────────────────
+
+;; JS `+`: if either operand is a string → string concat, else numeric.
 (define
   js-num-to-str-radix
   (fn
@@ -252,9 +259,6 @@
             (str "-" (js-num-to-str-radix-rec (- 0 int-n) radix ""))
             (js-num-to-str-radix-rec int-n radix "")))))))
 
-;; ── Arithmetic (JS rules) ─────────────────────────────────────────
-
-;; JS `+`: if either operand is a string → string concat, else numeric.
 (define
   js-num-to-str-radix-rec
   (fn
@@ -373,6 +377,7 @@
               (error
                 (str "TypeError: " (js-to-string key) " is not a function")))))))))
 
+;; Bitwise + logical-not
 (define
   js-object-builtin-method?
   (fn
@@ -385,7 +390,6 @@
       (= name "valueOf")
       (= name "toLocaleString"))))
 
-;; Bitwise + logical-not
 (define
   js-invoke-object-method
   (fn
@@ -407,13 +411,16 @@
       ((= name "toLocaleString") "[object Object]")
       (else js-undefined))))
 
-(define js-upper-case (fn (s) (js-case-loop s 0 "" true)))
-
 ;; ── Equality ──────────────────────────────────────────────────────
 
 ;; Strict equality (===): no coercion; js-undefined matches js-undefined.
+(define js-upper-case (fn (s) (js-case-loop s 0 "" true)))
+
 (define js-lower-case (fn (s) (js-case-loop s 0 "" false)))
 
+;; Abstract equality (==): type coercion rules.
+;; Simplified: number↔string coerce both to number; null == undefined;
+;; everything else falls back to strict equality.
 (define
   js-case-loop
   (fn
@@ -429,9 +436,6 @@
               ((cv (cond ((and to-upper? (>= cc 97) (<= cc 122)) (js-code-to-char (- cc 32))) ((and (not to-upper?) (>= cc 65) (<= cc 90)) (js-code-to-char (+ cc 32))) (else c))))
               (js-case-loop s (+ i 1) (str acc cv) to-upper?))))))))
 
-;; Abstract equality (==): type coercion rules.
-;; Simplified: number↔string coerce both to number; null == undefined;
-;; everything else falls back to strict equality.
 (define
   js-code-to-char
   (fn
@@ -491,15 +495,15 @@
       ((= code 122) "z")
       (else ""))))
 
-(define
-  js-invoke-method-dyn
-  (fn (recv key args) (js-invoke-method recv key args)))
-
 ;; ── Relational comparisons ────────────────────────────────────────
 
 ;; Abstract relational comparison from ES5.
 ;; Numbers compare numerically; two strings compare lexicographically;
 ;; mixed types coerce both to numbers.
+(define
+  js-invoke-method-dyn
+  (fn (recv key args) (js-invoke-method recv key args)))
+
 (define
   js-call-plain
   (fn
@@ -572,6 +576,13 @@
       ((dict-has? obj "__proto__") (js-in-walk (get obj "__proto__") skey))
       (else false))))
 
+;; ── Property access ───────────────────────────────────────────────
+
+;; obj[key] or obj.key in JS. Handles:
+;;   • dicts keyed by string
+;;   • lists indexed by number (incl. .length)
+;;   • strings indexed by number (incl. .length)
+;; Returns js-undefined if the key is absent.
 (define
   Error
   (fn
@@ -590,13 +601,6 @@
           nil)
         this))))
 
-;; ── Property access ───────────────────────────────────────────────
-
-;; obj[key] or obj.key in JS. Handles:
-;;   • dicts keyed by string
-;;   • lists indexed by number (incl. .length)
-;;   • strings indexed by number (incl. .length)
-;; Returns js-undefined if the key is absent.
 (define
   TypeError
   (fn
@@ -633,6 +637,7 @@
           nil)
         this))))
 
+;; Setter — mutates the dict. Returns the new value (JS assignment yields rhs).
 (define
   SyntaxError
   (fn
@@ -651,7 +656,10 @@
           nil)
         this))))
 
-;; Setter — mutates the dict. Returns the new value (JS assignment yields rhs).
+;; ── Short-circuit logical ops ─────────────────────────────────────
+
+;; `a && b` in JS: if a is truthy return b else return a. The thunk
+;; form defers evaluation of b — the transpiler passes (fn () b).
 (define
   ReferenceError
   (fn
@@ -670,10 +678,6 @@
           nil)
         this))))
 
-;; ── Short-circuit logical ops ─────────────────────────────────────
-
-;; `a && b` in JS: if a is truthy return b else return a. The thunk
-;; form defers evaluation of b — the transpiler passes (fn () b).
 (define
   js-function?
   (fn
@@ -686,17 +690,16 @@
         (= t "component")
         (and (= t "dict") (contains? (keys v) "__callable__"))))))
 
-(define __js_proto_table__ (dict))
-
 ;; ── console.log ───────────────────────────────────────────────────
 
 ;; Trivial bridge. `log-info` is available on OCaml; fall back to print.
-(define __js_next_id__ (dict))
+(define __js_proto_table__ (dict))
 
-(dict-set! __js_next_id__ "n" 0)
+(define __js_next_id__ (dict))
 
 ;; ── Math object ───────────────────────────────────────────────────
 
+(dict-set! __js_next_id__ "n" 0)
 (define
   js-get-ctor-proto
   (fn
@@ -778,11 +781,16 @@
         ((= trimmed "+Infinity") (js-infinity-value))
         ((= trimmed "-Infinity") (- 0 (js-infinity-value)))
         ((js-is-numeric-string? trimmed) (js-parse-num-safe trimmed))
-        (else (js-nan-value))))))
+        (else (js-nan-value))))))   ; deterministic placeholder for tests
+
 (define
   js-is-numeric-string?
-  (fn (s) (js-is-numeric-loop s 0 false false false)))   ; deterministic placeholder for tests
+  (fn (s) (js-is-numeric-loop s 0 false false false)))
 
+;; The global object — lookup table for JS names that aren't in the
+;; SX env. Transpiled idents look up locally first; globals here are a
+;; fallback, but most slice programs reference `console`, `Math`,
+;; `undefined` as plain symbols, which we bind as defines above.
 (define
   js-is-numeric-loop
   (fn
@@ -812,10 +820,6 @@
                   false)))
             (else false)))))))
 
-;; The global object — lookup table for JS names that aren't in the
-;; SX env. Transpiled idents look up locally first; globals here are a
-;; fallback, but most slice programs reference `console`, `Math`,
-;; `undefined` as plain symbols, which we bind as defines above.
 (define js-parse-num-safe (fn (s) (cond (else (js-num-from-string s)))))
 
 (define

lib/js/transpile.sx

@@ -159,6 +159,8 @@
       ((= name "undefined") (list (js-sym "quote") :js-undefined))
       ((= name "NaN") (list (js-sym "js-nan-value")))
       ((= name "Infinity") (list (js-sym "js-infinity-value")))
+      ((= name "eval") (js-sym "js-global-eval"))
+      ((= name "globalThis") (js-sym "js-global"))
       (else (js-sym name)))))
 
 ;; ── Unary ops ─────────────────────────────────────────────────────