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 3e (throw/try + ex-info): 632/632 compiled cases pass, 0 divergences; 2023/2655 out of subset (await clojure.core on Chez). Inc 3c (multi-arity + variadic fns) brought this to 619/619 — emit-fn lowers multi-arity fns to a Scheme case-lambda and variadic fns to a rest-arg lambda (the Scheme rest list is coerced to a jolt seq, nil when empty); inc 3e's throw/try/ex-info support pulled 13 more corpus cases into the subset.

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 3e (throw/try + ex-info): 334/355 non-macro core forms emit to Scheme (was 303 at inc 3d). :throw lowers to jolt-throw (Scheme raise of the raw jolt value, like the Janet compiled back end); :try lowers to guard (catch, class dropped → catch-all) + dynamic-wind (finally); ex-info is a native-op building the tagged jolt map, so the ex-data/ex-message/ex-cause tier fns read it over get for free. Remaining 21 gaps: :quote (8, needs RT symbols/lists), Java host interop .write/.isDirectory (6, io tier), letfn (4), declare/def-no-init (2), one edge (parse-uuid). Each is a clean next-increment target. The probe has a regression floor (raise it as gaps close).

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.