Chez Phase 1 (increment 3i): regex via vendored irregex

Closes the last clojure.core prelude emit gap (parse-uuid): the whole
non-macro core now lowers to Scheme (prelude reach 355/355).

A #"..." literal analyzes to a :regex IR node. The Chez back end emits
a jolt-regex value over irregex (Alex Shinn, BSD), vendored as the
vendor/irregex submodule -- a portable Scheme regex with PCRE/Java-style
string patterns and first-class Chez support. host/chez/regex.ss wraps
jolt's re-* surface over it: irregex-match -> re-matches (anchored),
irregex-search -> re-find, groups as Clojure [whole g1 ...] vectors,
re-seq as a jolt seq. re-pattern/re-matches/re-find/re-seq/regex? are
def-var!'d into clojure.core so prelude / -e code resolves them.

They stay OUT of the subset native-ops on purpose: irregex's
Unicode/property-class semantics differ from the seed's byte-PEG
approximation, so keeping them prelude-only avoids dragging
engine-difference divergences into the subset-parity corpus. The Janet
back end punts :regex to the interpreter (the seed compiles #"..." to a
Janet PEG), so the main language is unchanged.

Only two adaptations for Chez's top level: a cond-expand shim (Chez's is
library-only) and a normalizing error wrapper (silences irregex's 1-arg
error warnings). rt.ss load is ~0.18s.

emit-test 131/131 (regex literal + re-* parity vs the CLI oracle);
prelude reach 355/355; Chez subset 672/672, 0 divergences; full gate
green.

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "vendor/clojure-test-suite"]
 	path = vendor/clojure-test-suite
 	url = https://github.com/jank-lang/clojure-test-suite.git
+[submodule "vendor/irregex"]
+	path = vendor/irregex
+	url = https://github.com/ashinn/irregex.git

host/chez/emit.janet

@@ -369,6 +369,11 @@
     :throw (string "(jolt-throw " (emit (get node :expr)) ")")
     :try   (emit-try node)
     :quote (emit-quoted (get node :form))
+    # regex literal #"…" -> a jolt-regex value (regex.ss compiles the source via
+    # the vendored irregex). %j quotes+escapes the source; a backslash in the
+    # pattern becomes \\ in the Scheme string literal -> the 1-char backslash
+    # irregex expects (same escaping emit-const uses for strings).
+    :regex (string "(jolt-regex " (string/format "%j" (get node :source)) ")")
     # host interop (jolt-0kf5): (.method target arg*) -> (jolt-host-call "method"
     # target arg*). Only the methods the RT dispatcher (rt.ss) actually shims are
     # IN the subset; any other method is out of subset (a clean emit-time reject,

host/chez/regex.ss

@@ -0,0 +1,81 @@
+;; Phase 1 (jolt-cf1q.2) — regex on Chez via vendored irregex (jolt-i0s3).
+;;
+;; jolt's seed regex (src/jolt/regex.janet) compiles patterns to Janet's PEG
+;; engine; Chez has no regex at all. Rather than re-host that engine, we vendor
+;; Alex Shinn's irregex (vendor/irregex, BSD) — a portable Scheme regex with
+;; PCRE/Java-style STRING patterns — and wrap jolt's re-* surface over it.
+;;
+;; irregex maps cleanly onto the Clojure fns: irregex-match is an anchored
+;; whole-string match (= re-matches), irregex-search finds the first match
+;; anywhere (= re-find), irregex-match-substring extracts group N (0 = whole).
+;; Results follow Clojure shape: a 0-group match is the whole string; a grouped
+;; match is a jolt VECTOR [whole g1 ...] (a non-participating group is nil); a nil
+;; result is jolt-nil; re-seq is a jolt seq (nil when there are no matches).
+;;
+;; The re-* fns are def-var!'d into clojure.core so prelude / -e code resolves
+;; them at runtime (they're NOT subset native-ops: irregex's Unicode/property-
+;; class semantics differ from the seed's byte-PEG approximation, so they stay out
+;; of the subset-parity corpus). Loaded from rt.ss after def-var! is defined.
+
+;; irregex.scm is portable R[457]RS; two small adaptations for Chez's top level:
+;; a cond-expand at expression position (Chez's is library-only), and `error`
+;; called with a lone string (Chez's error wants who+msg). The wrapper normalizes
+;; both without changing behavior for valid patterns.
+(define-syntax cond-expand
+  (syntax-rules (else)
+    ((_ (else e ...)) (begin e ...))
+    ((_ (else e ...) c ...) (begin e ...))
+    ((_ (req e ...) c ...) (cond-expand c ...))
+    ((_) (if #f #f))))
+(define %chez-error error)
+(define (error . args)
+  (if (and (pair? args) (string? (car args)))
+      (apply %chez-error #f args)
+      (apply %chez-error args)))
+(load "vendor/irregex/irregex.scm")
+
+;; A jolt regex value: the source string (for printing / str) + the compiled
+;; irregex. regex? recognizes it; the printer renders #"source".
+(define-record-type regex-t (fields source irx) (nongenerative jolt-regex-v1))
+(define (jolt-regex source) (make-regex-t source (irregex source)))
+(define (jolt-regex? x) (regex-t? x))
+(define (jolt-re-pattern x) (if (regex-t? x) x (jolt-regex x)))
+
+;; An irregex match -> the Clojure result: whole string (no groups) or the
+;; [whole g1 ... gn] vector (nil for a non-participating group).
+(define (irx-result m)
+  (let ((n (irregex-match-num-submatches m)))
+    (if (= n 0)
+        (irregex-match-substring m 0)
+        (let loop ((i n) (acc '()))
+          (if (< i 0)
+              (apply jolt-vector acc)
+              (let ((s (irregex-match-substring m i)))
+                (loop (- i 1) (cons (if s s jolt-nil) acc))))))))
+
+(define (jolt-re-matches re s)
+  (let ((m (irregex-match (regex-t-irx (jolt-re-pattern re)) s)))
+    (if m (irx-result m) jolt-nil)))
+
+(define (jolt-re-find re s)
+  (let ((m (irregex-search (regex-t-irx (jolt-re-pattern re)) s)))
+    (if m (irx-result m) jolt-nil)))
+
+;; All non-overlapping matches, left to right. Advance past each match end (or by
+;; one on a zero-width match). nil when there are no matches (Clojure: seq-able as
+;; nil, so (if-let [m (re-seq ...)] ...) works), matching the seed.
+(define (jolt-re-seq re s)
+  (let ((irx (regex-t-irx (jolt-re-pattern re)))
+        (len (string-length s)))
+    (let loop ((start 0) (acc '()))
+      (let ((m (and (<= start len) (irregex-search irx s start))))
+        (if m
+            (let ((e (irregex-match-end-index m 0)))
+              (loop (if (> e start) e (+ start 1)) (cons (irx-result m) acc)))
+            (list->cseq (reverse acc)))))))
+
+(def-var! "clojure.core" "re-pattern" jolt-re-pattern)
+(def-var! "clojure.core" "re-matches" jolt-re-matches)
+(def-var! "clojure.core" "re-find" jolt-re-find)
+(def-var! "clojure.core" "re-seq" jolt-re-seq)
+(def-var! "clojure.core" "regex?" jolt-regex?)

host/chez/rt.ss

@@ -79,6 +79,11 @@
     (unless (hashtable-ref var-table k #f)
       (hashtable-set! var-table k (make-var-cell ns name jolt-unbound)))))
 
+;; regex (jolt-i0s3): defines regex-t + the re-* fns (def-var!'d into
+;; clojure.core), so it loads after def-var! and before the printer below (which
+;; renders a regex-t as #"source").
+(load "host/chez/regex.ss")
+
 ;; --- jolt number printing ----------------------------------------------------
 ;; jolt models every number as a Clojure double: integer-valued values print
 ;; without a ".0" (the Janet host prints (* 1.0 5) as "5", (/ 1 2) as "0.5").
@@ -115,6 +120,7 @@
     ((jolt-symbol? x) (let ((ns (symbol-t-ns x)))
                         (if (or (jolt-nil? ns) (not ns) (eq? ns '())) (symbol-t-name x)
                             (string-append ns "/" (symbol-t-name x)))))
+    ((regex-t? x) (string-append "#\"" (regex-t-source x) "\""))
     ((pvec? x) (let ((acc '())) (let loop ((i (fx- (pvec-count x) 1)))
                  (when (fx>=? i 0) (set! acc (cons (jolt-pr-str (pvec-nth-d x i jolt-nil)) acc)) (loop (fx- i 1))))
                  (string-append "[" (jolt-str-join acc) "]")))

jolt-core/jolt/analyzer.clj

@@ -21,6 +21,7 @@
                                form-vec? form-map? form-set? form-char?
                                form-literal? form-elements form-vec-items
                                form-map-pairs form-set-items form-special? compile-ns
+                               form-regex? form-regex-source
                                form-macro? form-expand-1 resolve-global
                                form-sym-meta host-intern! form-syntax-quote-lower
                                record-type? record-ctor-key form-position]]))
@@ -355,4 +356,8 @@
                                      (form-map-pairs form)))
      (form-set? form) (set-node (mapv #(analyze ctx % env) (form-set-items form)))
      (form-list? form) (analyze-list ctx form env)
+     ;; regex literal #"…" -> a :regex IR node (leaf). The Janet back end punts it
+     ;; (interpreter compiles via the seed PEG engine); the Chez back end emits a
+     ;; jolt-regex value over the vendored irregex.
+     (form-regex? form) {:op :regex :source (form-regex-source form)}
      :else (uncompilable "unsupported form"))))

src/jolt/backend.janet

@@ -781,6 +781,9 @@
       # punt to the interpreter, exactly as the analyzer used to before producing
       # a :host-call node (the Chez back end lowers it instead).
       :host-call (error "jolt/uncompilable: host method call")
+      # regex literal: the back end doesn't compile patterns — punt to the
+      # interpreter (the seed compiles #"…" to a Janet PEG). Chez emits jolt-regex.
+      :regex (error "jolt/uncompilable: regex literal")
       (error (string "backend: unhandled op " (node :op))))))
 
 (defn emit-ir

src/jolt/host_iface.janet

@@ -46,6 +46,13 @@
       (phm/phm? form)))
 (defn h-set? [form] (and (struct? form) (= :jolt/set (form :jolt/type))))
 (defn h-char? [form] (and (struct? form) (= :jolt/char (form :jolt/type))))
+# A regex literal #"…" reads as a tagged form {:jolt/type :jolt/tagged :tag :regex
+# :form "source"}. The analyzer lowers it to a :regex IR node (Chez emits a
+# jolt-regex value; the Janet back end punts to the interpreter, which compiles it
+# via the seed PEG engine).
+(defn h-regex? [form]
+  (and (struct? form) (= :jolt/tagged (form :jolt/type)) (= :regex (form :tag))))
+(defn h-regex-source [form] (form :form))
 
 (defn h-literal? [form]
   (or (nil? form) (boolean? form) (number? form) (string? form)
@@ -254,6 +261,7 @@
    "form-sym-meta" h-sym-meta
    "form-list?" h-list? "form-vec?" h-vector? "form-map?" h-map?
    "form-set?" h-set? "form-char?" h-char? "form-literal?" h-literal?
+   "form-regex?" h-regex? "form-regex-source" h-regex-source
    "form-elements" h-elements "form-vec-items" h-vector-items
    "form-map-pairs" h-map-pairs "form-set-items" h-set-items
    "form-special?" h-special? "compile-ns" h-current-ns "form-macro?" h-macro?

test/chez/README.md

@@ -72,19 +72,21 @@ catalogs the gaps; macros are skipped (analyze-time only, not a runtime value):
 
     JOLT_CHEZ_PRELUDE=1 janet test/chez/core-prelude-probe.janet
 
-Baseline after inc 3h (host-interop method calls): **354/355 non-macro core forms
-emit** to Scheme (was 348 at inc 3g, 342 at inc 3f). A `.method` call now analyzes
-to a `:host-call` IR node; the Chez emitter lowers it to a `jolt-host-call`
-dispatch for the methods the RT shims — `.write` → port `display`, `.isDirectory`
-→ `file-directory?`, `.listFiles` → `directory-list` — closing the io tier's
-print-method defmethods and `file-seq` (now 20/20). Any other method is out of
-subset (a clean emit-time reject, so it can't masquerade as a compiled-but-broken
-divergence); the Janet back end punts ALL `:host-call` to the interpreter. Prior
-incs: `:quote` reconstructs the raw reader form as RT constructors; `:throw` →
-`jolt-throw`, `:try` → `guard` + `dynamic-wind`, `ex-info` native-op; `letfn` →
-`letrec*`; `declare`/def-no-init → a reserved var cell. Remaining 1 gap: the regex
-literal in `parse-uuid` (needs a regex engine on Chez — see jolt issue). The probe
-has a regression floor (354).
+Baseline after inc 3i (regex): **355/355 non-macro core forms emit** to Scheme —
+the whole non-macro clojure.core now lowers. inc 3i closed the last gap, the regex
+literal in `parse-uuid`: a `#"…"` literal lowers to a `:regex` IR node and the Chez
+emitter emits a `jolt-regex` value over **vendored irregex** (Alex Shinn, BSD,
+`vendor/irregex` submodule) — a portable Scheme regex with PCRE/Java-style string
+patterns. `re-pattern`/`re-matches`/`re-find`/`re-seq`/`regex?` are `def-var!`'d
+into clojure.core (`host/chez/regex.ss`); they stay OUT of the subset native-ops
+(irregex's Unicode/property-class semantics differ from the seed's byte-PEG
+approximation), so they resolve in prelude mode — the path the assembled prelude
+takes — without dragging engine-difference divergences into the subset corpus. The
+Janet back end punts `:regex` to the interpreter (the seed compiles `#"…"` to a
+Janet PEG). Prior incs: inc 3h `.method` → `:host-call` (`jolt-host-call` for
+`.write`/`.isDirectory`/`.listFiles`); `:quote`, `:throw`, `:try`, `ex-info`,
+`letfn` → `letrec*`, `declare`/def-no-init → reserved var cell. The probe has a
+regression floor (355) — every non-macro core form must keep emitting.
 
 Prior, inc 3b (seq tier + dynamic IFn, jolt-5pso): 595/595 compiled, 0 divergences,
 2060/2655 out of subset. The seq tier brought up a list/lazy-seq type with

test/chez/core-prelude-probe.janet

@@ -98,7 +98,7 @@
 
 # Regression floor (raise it as new IR ops / RT shims land, like the suite
 # baseline). Fails if prelude emit reach drops below the recorded baseline.
-(def reach-floor 354)
+(def reach-floor 355)
 (when (< compiled reach-floor)
   (printf "REGRESSION: prelude emit reach %d < floor %d" compiled reach-floor)
   (os/exit 1))

test/chez/emit-test.janet

@@ -300,6 +300,42 @@
   (ok "runtime .isDirectory \"/\" = true" (and (= code 0) (= out "true"))
       (string "chez=" out " | " err)))
 
+# 3m) regex (jolt-i0s3): the #"…" literal lowers to a jolt-regex value over the
+#   vendored irregex; re-pattern/re-matches/re-find/re-seq/regex? are def-var!'d
+#   into clojure.core (not subset native-ops — irregex's Unicode/property
+#   semantics differ from the seed's byte-PEG), so they resolve in PRELUDE mode,
+#   the path the assembled prelude takes. Parity vs the CLI oracle on standard
+#   PCRE patterns both engines agree on.
+(defn run-prelude [src]
+  (emit/set-prelude-mode! true)
+  (def r (protect (emit/emit (backend/analyze-form ctx (in (r/parse-next src) 0)))))
+  (emit/set-prelude-mode! false)
+  (if (not (r 0)) [:emit-err (r 1) ""]
+    (do
+      (spit "/tmp/chez-regex-prelude.ss" (emit/program @[] (r 1)))
+      (def proc (os/spawn ["chez" "--script" "/tmp/chez-regex-prelude.ss"] :p {:out :pipe :err :pipe}))
+      (def out (ev/read (proc :out) 0x100000))
+      (def err (ev/read (proc :err) 0x100000))
+      [(os/proc-wait proc) (string/trim (if out (string out) "")) (string/trim (if err (string err) ""))])))
+
+# bare #"…" literal runs in plain subset mode (the :regex node needs no core fn).
+(each src ["#\"\\d+\"" "(do #\"a.c\")"]
+  (let [[code out err] (d/run-on-chez ctx src) want (cli-oracle src)]
+    (ok (string "regex literal: " src) (and (= code 0) (= out want))
+        (string "chez=" out " janet=" want " | " err))))
+
+# re-* surface via prelude mode (def-var!'d fns), parity vs the CLI oracle.
+(each src ["(re-matches #\"\\d+\" \"123\")"
+           "(re-matches #\"\\d+\" \"12a\")"
+           "(re-find #\"\\d+\" \"abc123def\")"
+           "(re-find #\"([a-z])(\\d)\" \"--a1--\")"
+           "(re-seq #\"\\d+\" \"a1b22c333\")"
+           "(regex? #\"\\d+\")"
+           "(re-matches #\"[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\" \"550e8400-e29b-41d4-a716-446655440000\")"]
+  (let [[code out err] (run-prelude src) want (cli-oracle src)]
+    (ok (string "regex: " src) (and (= code 0) (= out want))
+        (string "chez=" out " janet=" want " | " err))))
+
 # 3h) prelude mode (inc 3d): emitting clojure.core ITSELF, a core->core ref must
 #   lower to a runtime var-deref instead of being rejected as "out of subset".
 #   `frequencies` is a core fn but not a native-op, so it exercises the switch.

vendor/irregex

@@ -0,0 +1 @@
+Subproject commit c948a704fc732914a243c1643bfe359913d11c7b