Chez Phase 2 (inc L): var def-time metadata (jolt-zikh)

Capture a def's reader metadata on the Chez var. The :def emit now lowers a def
with non-empty metadata to def-var-with-meta!, which stores the user meta
(^:private / ^Type tag / docstring -> {:doc}) in an eq side-table keyed by the
var-cell. jolt-meta of a var-cell merges that onto {:ns :name} derived from the
cell, so every var reports {:ns :name} like Clojure with the def-time meta
layered on. (^{:map} metadata on a def name stays uncompilable for the compiler
generally — analyzer rejects it, the Janet back end punts to its interpreter,
which Chez lacks — so it's out of subset, not a meta-capture gap.)

Added natives-meta.ss to the prelude-cache fingerprint. Prelude parity
1969 -> 1972, 0 new divergences; the three var-metadata allowlist entries
(^:private / ^Type tag / docstring) dropped. New focused gate
test/chez/_var_meta.janet.

host/chez/emit.janet

@@ -218,6 +218,15 @@
     (or (struct? form) (table? form)) (emit-quoted-map form)
     (errorf "emit-quoted: unsupported quoted form %p" form))))
 
+# A def's :meta is a jolt map value (Janet struct/table or phm). Non-empty?
+# (a plain def carries {} — keep it on the lean def-var! path).
+(defn- jmeta-nonempty? [m]
+  (cond
+    (nil? m) false
+    (phm/phm? m) (> (length (phm/phm-to-struct m)) 0)
+    (or (struct? m) (table? m)) (> (length m) 0)
+    false))
+
 (defn- emit-binding [b]
   (def b (vv b))
   (string "(" (munge (get b 0)) " " (emit (get b 1)) ")"))
@@ -481,9 +490,16 @@
     :fn    (emit-fn node)
     # (def name) with no init (declare): reserve the var cell (declare-var!
     # doesn't clobber an existing root) so a forward reference resolves.
-    :def   (if (get node :no-init)
+    # A def with non-empty reader metadata (^:private / ^Type tag / docstring ->
+    # {:doc}) lowers to def-var-with-meta! so (meta (var x)) sees it (jolt-zikh).
+    :def   (cond
+             (get node :no-init)
              (string "(declare-var! " (chez-str-lit (get node :ns)) " "
                      (chez-str-lit (get node :name)) ")")
+             (jmeta-nonempty? (get node :meta))
+             (string "(def-var-with-meta! " (chez-str-lit (get node :ns)) " "
+                     (chez-str-lit (get node :name)) " " (emit (get node :init)) " "
+                     (emit-quoted (get node :meta)) ")")
              (string "(def-var! " (chez-str-lit (get node :ns)) " "
                      (chez-str-lit (get node :name)) " " (emit (get node :init)) ")"))
     (errorf "emit: unhandled op %p" (get node :op)))))

host/chez/jolt-chez.janet

@@ -20,7 +20,7 @@
   (each f ["host/chez/emit.janet" "host/chez/driver.janet" "host/chez/rt.ss"
            "host/chez/values.ss" "host/chez/collections.ss" "host/chez/seq.ss"
            "host/chez/atoms.ss" "host/chez/predicates.ss" "host/chez/regex.ss"
-           "host/chez/ns.ss" "host/chez/post-prelude.ss"]
+           "host/chez/ns.ss" "host/chez/post-prelude.ss" "host/chez/natives-meta.ss"]
     (array/push parts (slurp f)))
   (string/slice (string (hash (string/join parts))) 0))
 

host/chez/natives-meta.ss

@@ -12,6 +12,13 @@
 (define (jolt-meta x)
   (cond
     ((symbol-t? x) (let ((m (symbol-t-meta x))) (if (jolt-nil? m) jolt-nil m)))
+    ;; a var's meta is {:ns :name} (derived from the cell) + any def-time user
+    ;; meta from rt.ss's var-meta-table (jolt-zikh).
+    ((var-cell? x)
+     (let ((user (hashtable-ref var-meta-table x #f)))
+       (jolt-assoc (if user user (jolt-hash-map))
+                   jolt-kw-var-ns (var-cell-ns x)
+                   jolt-kw-var-name (var-cell-name x))))
     ((or (pvec? x) (pmap? x) (pset? x) (cseq? x) (empty-list-t? x) (jrec? x) (procedure? x))
      (hashtable-ref meta-table x jolt-nil))
     (else jolt-nil)))

host/chez/rt.ss

@@ -82,6 +82,16 @@
 ;; (pr-str (def x 1)) is "#'ns/x". The prelude's def-var! forms discard the
 ;; return, so this is transparent there.
 (define (def-var! ns name v) (let ((c (jolt-var ns name))) (var-cell-root-set! c v) (var-cell-defined?-set! c #t) c))
+;; var def-time metadata (jolt-zikh): the :def emit passes the def's reader meta
+;; (^:private / ^Type tag / docstring -> {:doc}) here, stored in an eq side-table
+;; keyed by the cell. jolt-meta (natives-meta.ss) merges it onto {:ns :name},
+;; which it derives from the cell — so EVERY var (plain def, native-op, declare)
+;; reports {:ns :name} like Clojure, with the user meta layered on when present.
+(define var-meta-table (make-eq-hashtable))
+(define jolt-kw-var-ns (keyword #f "ns"))
+(define jolt-kw-var-name (keyword #f "name"))
+(define (def-var-with-meta! ns name v m)
+  (let ((c (def-var! ns name v))) (hashtable-set! var-meta-table c m) c))
 ;; declare / (def name) with no init: reserve the cell ONLY if absent. An
 ;; existing root is left intact — Clojure's (def x) with no init does not clobber
 ;; a prior binding (do (def x 7) (def x) x) => 7. Returns the cell either way.

test/chez/_var_meta.janet

@@ -0,0 +1,45 @@
+# jolt-zikh — var def-time metadata capture (^:private / ^Type tag / docstring).
+# (meta (var v)) must carry the def-time reader metadata + :ns/:name, matching the
+# JVM-canonical build/jolt. TDD harness: bin/jolt-chez -e per case, last line ==
+# expected.
+#
+#   janet test/chez/_var_meta.janet
+(def jolt-bin (or (os/getenv "JOLT_BIN") "bin/jolt-chez"))
+
+(def cases
+  # NOTE: ^{:map} metadata on a def name (e.g. (def ^{:doc "hi"} dv 1)) reads as
+  # (def (with-meta name m) v) and is uncompilable for the COMPILER generally
+  # (analyzer.clj rejects it; the Janet back end punts to its interpreter, which
+  # Chez lacks) — out of subset, not a meta-capture gap. Shorthand ^:kw / ^Type
+  # and the docstring form keep the name a plain symbol, so they're in scope.
+  [["^:private on var"   "(do (def ^:private pv 1) (:private (meta (var pv))))"      "true"]
+   ["^Type tag on var"   "(do (def ^String tv \"a\") (:tag (meta (var tv))))"        "String"]
+   ["(def name doc val)"  "(do (def dv2 \"hi\" 1) (:doc (meta (var dv2))))"          "hi"]
+   ["meta carries :name"  "(do (def mv 1) (:name (meta (var mv))))"                  "mv"]
+   ["meta carries :ns"    "(do (def nv 1) (:ns (meta (var nv))))"                    "user"]
+   ["plain def: no user meta" "(do (def pl 1) (nil? (:private (meta (var pl)))))"    "true"]])
+
+(defn run-capture [expr]
+  (def proc (os/spawn [jolt-bin "-e" expr] :p {:out :pipe :err :pipe}))
+  (def out (ev/read (proc :out) 0x100000))
+  (def err (ev/read (proc :err) 0x100000))
+  (def code (os/proc-wait proc))
+  (def lines (filter (fn [l] (not (empty? l)))
+                     (string/split "\n" (string/trim (if out (string out) "")))))
+  [code (if (empty? lines) "" (last lines)) (if err (string err) "")])
+
+(var pass 0)
+(def fails @[])
+(each [label expr expected] cases
+  (def [code got err] (run-capture expr))
+  (cond
+    (not= code 0) (array/push fails [label (string "exit " code "; err: " (string/trim err))])
+    (= got expected) (++ pass)
+    (array/push fails [label (string "want `" expected "`, got `" got "`")])))
+
+(printf "\n_var_meta parity [%s]: %d/%d passed" jolt-bin pass (length cases))
+(when (> (length fails) 0)
+  (printf "%d FAIL(s):" (length fails))
+  (each [l m] fails (printf "  FAIL [%s] %s" l m)))
+(flush)
+(os/exit (if (empty? fails) 0 1))

test/chez/run-corpus-prelude.janet

@@ -69,14 +69,9 @@
    "defmethod overrides a record, top level" true
    "defmethod fires nested in a map" true
    "defmethod fires through prn" true
-   "methods table inspectable" true
-   # Phase 2 inc I (jolt-n7rz) made (var x)/#'x emit + the static var ops run; a
-   # var's def-time metadata (^:private / ^Type tag / docstring) isn't captured on
-   # the Chez var-cell yet, so (meta (var v)) is nil — var-metadata capture is a
-   # later increment.
-   "^:private on var" true
-   "^Type tag on var" true
-   "(def name doc val) doc" true})
+   # var def-time metadata (^:private / ^Type tag / docstring) is now captured on
+   # the Chez var-cell (jolt-zikh), so those three cases pass.
+   "methods table inspectable" true})
 
 (def ctx (d/make-ctx))
 
@@ -190,8 +185,11 @@
 # jolt-yxqm (namespace value model — find-ns/ns-name/all-ns/resolve/ns-publics/
 # in-ns/*ns* over the var-table + a jns ns value; native-op var cells so
 # (resolve '+) is a var; *ns* bound to the user ns) 1969.
+# jolt-zikh (var def-time metadata — :def emit passes reader meta to
+# def-var-with-meta!; (meta (var v)) is {:ns :name} + ^:private/^Type tag/
+# docstring) 1972.
 # Strided runs scale down.
-(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "1969")))
+(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_PRELUDE_FLOOR") "1972")))
 (def floor (if (os/getenv "JOLT_CORPUS_LIMIT") 0 base-floor))
 (when (or (> (length diverged) 0) (< pass floor))
   (printf "REGRESSION: pass %d < floor %d or %d new divergence(s)" pass floor (length diverged)))