jolt/test/chez/README.md

Chez port — Phase 0 test contract harness

The host-neutral correctness gate for the Chez re-host (epic jolt-cf1q). The spec corpus is data, so the SAME contract validates every host.

Files

• extract-corpus.janet — parses test/spec/*.janet (defspec …) tables as data and writes corpus.edn (2655 [label expected actual] cases). The file is valid as BOTH EDN (a future Chez-jolt runner) and Janet data (the runner below). Regenerate: janet test/chez/extract-corpus.janet.
• corpus.edn — the extracted contract (generated; checked in for convenience).
• run-corpus.janet — drives a TARGET jolt binary, one fresh subprocess per case (fresh ctx = per-case isolation), checking (= expected actual) prints true at the CLI, or that a :throws case exits non-zero. Pluggable target:
  • janet test/chez/run-corpus.janet # default build/jolt
  • JOLT_BIN=build/jolt-chez janet test/chez/run-corpus.janet # Phase 1+
  • JOLT_CORPUS_LIMIT=400 … # every-Nth stride, fast
• known-divergences.edn — allowlist of cases that diverge at the CLI boundary. The gate fails only on a NEW divergence; known ones are reported but tolerated.
• values-test.ss / ../../host/chez/values.ss — Phase 0a value model + tests.

The reference baseline (2026-06-17, Janet build/jolt, compile mode)

2641/2655 pass; 14 known divergences. They split into:

• interpret-vs-compile leniency — :throws cases where interpret mode raises but compile mode returns (< nil, > with nil, neg? keyword, max/min-key on non-numbers). Several are also non-canonical vs JVM Clojure.
• invoke-collection-as-fn — the transient / invokable lookup suite invokes transients/collections as fns (((transient {:x 7}) :x)); compile mode (and JVM Clojure) reject it.
• xml-seq walks — one structural case.

The compile-only Chez host (JVM-canonical oracle) should MATCH OR FIX these. The gate's job is to catch regressions the port introduces, not to bless these.

Why the CLI boundary

The runner tests through jolt -e, exactly how the Chez host will be exercised — not the in-process eval-string the Janet defspec harness uses. The two differ on a handful of cases (the allowlist), and the CLI boundary is the portable one.

Phase 1 — first parity number (subset probe)

The full run-corpus.janet gate drives an -e-capable jolt binary; the Chez host can't answer arbitrary -e until all of clojure.core is bootstrapped onto Chez (Phase 2). Until then, run-corpus-chez.janet reports parity for the subset the Phase-1 back end (host/chez/emit.janet) can already compile: each case is run through the live analyzer → Scheme emitter → Chez via host/chez/driver. Cases that reference unimplemented stdlib/host fns fail to EMIT (a clean compile-time signal) and are counted "out of subset", not as divergences.

JOLT_CHEZ_CORPUS=1 janet test/chez/run-corpus-chez.janet

Baseline after inc 3g (letfn + declare): 672/672 compiled cases pass, 0 divergences; 1986/2658 out of subset (await clojure.core on Chez). Inc 3e (throw/try + ex-info) was 632/632; inc 3f's quote support + a seq.ss fix (empty map/filter results are () not nil, matching Clojure) reached 664/664; inc 3g (letfn -> Scheme letrec*, declare/def-no-init -> a reserved var cell) pulled 8 more corpus cases into the subset. emit-fn lowers multi-arity fns to a Scheme case-lambda and variadic fns to a rest-arg lambda (rest list coerced to a jolt seq, nil when empty).

Phase 1 — clojure.core prelude emission (inc 3d, jolt-ocvi)

The -e-capable jolt-chez path: emit the clojure.core tiers (jolt-core/clojure/core/NN-*.clj) through the same analyzer → emit pipeline as a Scheme PRELUDE of def-var! forms, so user code's (var-deref "clojure.core" …) resolves the fn at runtime. emit/set-prelude-mode! flips a switch: in the default (subset) mode a non-native clojure.core ref is rejected ("out of subset"); in prelude mode it lowers to a runtime var-deref so core fns chain through each other. Host interop (:host) and unhandled IR ops still error in both modes — those are the real gaps that need a hand-written RT shim or new emit support.

core-prelude-probe.janet (gated behind JOLT_CHEZ_PRELUDE=1) measures reach and 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 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.

Phase 1 — the assembled prelude: -e-capable jolt-chez (inc 3j, jolt-9ziu)

Once the whole non-macro clojure.core emits (inc 3i), the milestone is to ASSEMBLE it: driver/emit-core-prelude emits every non-macro core form across the dependency-ordered tiers as a def-var! (prelude mode), concatenated into a Scheme prelude. bin/jolt-chez -e EXPR loads rt.ss + that prelude + a post-prelude override, emits the user expression in prelude mode, and runs it on Chez — an -e-capable jolt-chez (analysis on Janet, execution on Chez). The prelude is cached on disk keyed by a fingerprint of the core sources + the RT.

run-corpus-prelude.janet is the full parity gate this opens (the prelude-backed sibling of run-corpus-chez.janet): it assembles the prelude once, then runs every corpus case with all of core present, bucketing the result —

JOLT_CHEZ_PRELUDE_CORPUS=1 janet test/chez/run-corpus-prelude.janet
JOLT_CORPUS_LIMIT=200 …    (every-Nth stride, fast)

Parity baseline: inc 3j 1220/2497; 3k (converters, jolt-t6cr) 1326; 3l (transients, jolt-kl2l) 1382; 3m (numeric-edge emit + variadic assoc!, jolt-q3w8) 1407/2497, 0 NEW divergences (14 allowlisted: dynamic vars *ns*/*clojure-version*/*unchecked-math*, var/*ns* rendering, class names, eval-order, with-open — all deferred Phase-2 / dynamic-var gaps).

• inc 3k host/chez/converters.ss: str/subs/vec/keyword/symbol/compare/ int/double/gensym (seed natives — str reuses the printer, compare is the 3-way port, the symbol no-ns sentinel is #f to match emit's quoted-symbol lowering so (= 'x (symbol "x")) holds).

• inc 3l host/chez/transients.ss: transient/persistent!/conj!/assoc!/ dissoc!/disj!/pop! as copy-on-write over the persistent collections (correct semantics, no in-place perf), plus persistent disj. get/count/contains? are redefined to see THROUGH a transient (frequencies/group-by do (get tm k) on a transient map); vector? on a transient vector is false, which group-by relies on.

• inc 3m: ##Inf/##-Inf/##NaN emitted to bare inf/nan (unbound in Chez); emit-const now lowers them to +inf.0/-inf.0/+nan.0, the -e printer renders inf/-inf/nan and str renders Infinity/-Infinity/NaN (Clojure). Plus variadic assoc!. (str of inf inside a collection still wants the long form — the Phase-2 recursive str renderer — so [inf inside coll] is allowlisted.)

• inc 3n host/chez/natives-seq.ss (jolt-y6mv): the dominant prelude-parity crash bucket was apply non-procedure jolt-nil — core fns calling seed-native seq fns (src/jolt/core_coll.janet) that have no Chez shim, so var-deref yields jolt-nil. A static scan of the assembled prelude found 52 referenced-but-undefined clojure.core names; this increment shims the safe, high-value seq fns: mapcat/ take-while/drop-while/partition (collection arities — the 1-arg transducer forms are jolt-kxsr), sort (compare default; a comparator may return a 3-way number or a boolean less-than), and reduced/reduced? — a jolt-reduced record in seq.ss that reduce short-circuits on and deref unwraps (so unreduced works). identical? = jolt= (the seed's definition). list? was deferred: a Chez lazy seq and a list are both cseq, so it can't be told apart without a distinct list type (a real divergence risk).

• inc 3o transducer arities (jolt-kxsr): the 1-arg map/filter/remove/take/ drop/take-while/drop-while/mapcat return a transducer (fn [rf] rf'), and into gets a 3-arg (into to xform from). These were the cdr () is not a pair / incorrect number of arguments crash bucket: the emitter lowers (map f) / (into to xf from) at the wrong arity to the bare native procedure (the value-position path), so the fix is RT-side — case-lambda the seq procedures and jolt-into. The td-* factories are ported from the seed (core_coll.janet); a reduced step stops the fold via reduce-seq's short-circuit. transduce/comp/ completing are overlay and compose over these for free.

• inc 3p misc seq/regex gaps (jolt-y1zq): 0-arg (conj) -> [], 0-arg (conj!) -> a fresh transient vector, nth sees through a transient (like get/count/contains?), and irregex \p{...}/\P{...} property classes translate to the seed's ASCII char classes (regex.ss; \p{L}->[a-zA-Z], \p{N}->[0-9], \p{Ps}->[([{], …) — ASCII-only (the seed counts UTF-8 high bytes as letters, which a Unicode-char Scheme string can't reproduce; the corpus tests ASCII, where they agree) and clojure.math/PI (missing ns).

  Two pre-existing bugs surfaced here and are tracked (not replicated):

  • jolt-x0os (Chez emit) — a non-ASCII string literal emits an invalid Chez hex escape ((str "héllo") -> "read: invalid character \ in string hex escape"). This is why p{L} utf-8 still crashes (the \p{L} translation is correct and matches non-ASCII, but the input string can't be emitted). A crash, not a divergence.
  • jolt-ea9k (seed) — assoc! on a transient accepts ODD args and assigns nil to the trailing key (plain assoc correctly throws; Clojure's assoc! throws too). The Chez host throws (Clojure-correct), so the 4 odd arg … corpus rows — which encode the seed's lenient behavior — sit in the crash bucket until the seed is fixed and those spec rows are updated to :throws.

The remaining buckets are the punch-list the next increments chase: ~361 emit-fail (genuine host interop — qualified Java/Janet refs, runtime defmacro/eval, out of the analyzer's subset) and the runtime crashes still dominated by apply jolt-nil (more host-coupled natives without a shim: meta/with-meta, format, the clojure.string natives, bit ops, var/volatile/future/thread-binding ops), plus the small jolt-y1zq tail (0-arg conj, \p{} regex classes, a few one-offs) and multimethod dispatch (Phase 2 jolt-9ls5).

Two host shims landed with the prelude. host/chez/atoms.ss: atom/deref/swap!/ reset! (+ compare-and-set!/swap-vals!/reset-vals!) — host-coupled mutable cells the overlay assumes are native; needed at the prelude's LOAD time (global-hierarchy = (atom (make-hierarchy))). host/chez/predicates.ss: the type predicates + name/namespace/boolean the overlay assumes are seed natives (nil?/number?/string?/map?/vector?/set?/seq?/coll?/fn?/…), matching the seed's strict semantics. host/chez/post-prelude.ss re-asserts char?/atom? AFTER the prelude — the overlay implements those two by reading a value's :jolt/type key (a Janet-host assumption that's false for Chez-native chars/atoms), and its def-var! would otherwise clobber the correct native shims.

The 8 print-method/print-dup defmulti/defmethod forms (50-io) can't LOAD yet (no multimethod runtime on Chez — Phase 2); a silent load guard in the assembled prelude lets the rest load and turns them into lazy gaps.

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 first/rest/next/seq/cons/list, map/filter/reduce/into/remove, range/take/drop/concat/apply, keys/vals, and nth/peek/pop over seqs; dynamic IFn dispatch (a keyword/vector/coll held in a local and called as a fn) routes through the jolt-invoke fallback, closing the 3 ex-known divergences. The probe exits non-zero on any NEW divergence.

(Prior, inc 3a: 433/436 compiled, 3 known IFn divergences, 2219 out of subset. Inc 2: 182/182 compiled, 0 divergences, 2473 out of subset.)

It's a slow report (a Chez subprocess per case), so it's gated behind JOLT_CHEZ_CORPUS out of the default suite, like the benches. test/chez/emit-test.janet is the fast Phase-1 unit gate (real analyzer → Chez parity for fib/mandelbrot + collections + regressions); both skip cleanly when chez isn't on PATH.