45876998ad
Bring the docs in line with the actual implementation now that Chez is the sole substrate. Deleted the migration/spike/handoff artifacts that only documented the Janet era or the port effort: the port plan, phase-0 and foundational-runtime spike writeups (+ the stray root-level copy), the self-hosting design notes, the architecture-refactor plan, and spike/chez/RESULTS.md. Rewrote the current reference docs against the Chez facts: building-and-deps and tools-deps (no jpm/build step — bin/joltc off the checked-in seed, deps via jolt.deps into ~/.jolt/gitlibs), libraries (SQLite is built-in jdbc.core over libsqlite3, not a Janet driver), the conformance/spec test-flow docs (the Chez corpus runner + certify, no .janet harnesses), and the transient / type-hint / seed-overlay design notes (Chez representations: mutable transients, flat copy-on-write vectors, HAMT maps, the seed/overlay twin). Fixed the README collections line (vectors aren't 32-way tries) and added the ffi/transient gate targets. rfc 0001's numerics open-question is resolved (the Scheme tower). Renamed the built-in HTTP adapter to jolt.http.server only (dropped the ring-janet.adapter alias — a Janet-era name).
114 lines
6.2 KiB
Markdown
114 lines
6.2 KiB
Markdown
# The jolt conformance spec
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This directory defines jolt's behavior as a **host-neutral, executable language
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specification**: a data file of cases, certified against reference Clojure, with a
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feature profile that lets any runtime declare a conformance *level*. The goal is to
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make hosting jolt on a new runtime (and proving it correct) a mechanical exercise:
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read one data file, run each case, compare, report.
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## The artifacts
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| File | Role | Generated by |
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|------|------|--------------|
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| `test/chez/corpus.edn` | **The spec.** ~2900 cases of `{:suite :label :expected :actual}`, `:expected` **sourced from reference JVM Clojure**. | `test/conformance/regen-corpus.clj` |
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| `test/conformance/profile.edn` | Per-case **feature classification** — which non-portable cases need which host capability. | `certify.clj --profile` |
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| `test/conformance/known-divergences.edn` | The few rows whose JVM value is an opaque host object that can't round-trip to readable source (Java arrays/transients/atoms/beans/proxies print as `#object[..@addr]`), so the corpus keeps jolt's value. | `regen-corpus.clj` leftovers, hand-checked |
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| `test/conformance/regen-corpus.clj` | Sources every `:expected` from reference **JVM Clojure** in one process. | — |
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| `test/conformance/certify.clj` | Certifies `:expected` against reference **JVM Clojure**; gates on new/stale divergences; emits the profile. | — |
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`corpus.edn` is **JVM-sourced**: `regen-corpus.clj` evaluates each case's `:actual`
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on reference JVM Clojure and writes the JVM value as `:expected`. **`corpus.edn` is
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the canonical, frozen contract**: it is what every runtime consumes, what
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`certify.clj` certifies, and where new cases are authored directly.
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## Row schema
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```edn
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{:suite "numbers / arithmetic" ; grouping; "<suite> :: <label>" is the case id
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:label "integer add" ; unique within a suite
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:actual "(+ 1 2)" ; Clojure source to evaluate
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:expected "3"} ; Clojure source whose value it must equal,
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; or the keyword :throws
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```
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- `[:suite :label]` is the **canonical, unique case id** (the generator
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disambiguates duplicate labels with ` (N)`).
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- Comparison is **value-equality** (`=`), never string/printed-form — so map/set
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iteration order never matters.
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- `:expected :throws` asserts evaluating `:actual` raises.
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## The oracle: reference JVM Clojure
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Historically every `:expected` was hand-written. `certify.clj` removes that
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weakness: it evaluates every `:actual` (and `:expected`) on **JVM Clojure** in a
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fresh `user` namespace and checks jolt's `:expected` against what real Clojure
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produces. Of ~2740 vanilla-certifiable rows, **>2660 match reference Clojure
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exactly**. The rest are classified (see below) — none are silently wrong.
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```sh
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clojure -M test/conformance/certify.clj # gate
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clojure -M test/conformance/certify.clj test/chez/corpus.edn --edn r.edn # + report
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clojure -M test/conformance/certify.clj test/chez/corpus.edn --profile test/conformance/profile.edn
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```
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The gate fails only on a **new** (unclassified) divergence or a **stale**
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allowlist entry; flaky timing-dependent cases (`future-cancel`) are tolerated.
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## Conformance levels & the feature profile
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Not every case is portable: some assume a host capability jolt has on one runtime
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but not another (Java interop, real threads, BigDecimal). `profile.edn` classifies
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each **non-portable** case by the feature it requires. Cases *not* in the profile
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are **portable** — they must pass on any faithful Clojure.
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A runtime's **conformance level** = portable cases + the feature families it
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implements. Current profile (≈2670 portable, ≈249 non-portable):
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| Feature | Meaning |
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|---------|---------|
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| `:numerics/double-only` | all-double numeric model — no Ratio/BigDecimal/float; `(/ 1 2)` ⇒ `0.5` |
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| `:concurrency/snapshot` | isolated-heap futures/agents/pmap — captured atoms are snapshotted, not shared |
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| `:host/jvm-interop` | Java classes / `instance?` on host classes / proxy / bean / definterface |
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| `:host/arrays` | Java arrays (`into-array`, `int-array`, …) |
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| `:async/core-async` | `clojure.core.async` channels/`go` |
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| `:runtime/eval` | runtime `eval` / `load-string` |
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| `:reader/jolt` | jolt reader features (`#?(:jolt …)`) + syntax-quote literal collapse |
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| `:printer/jolt` | jolt's rendering of transients/atoms/`print-method` overrides |
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| `:strictness/jolt` | intentionally stricter (throws on odd `assoc!` args, etc.) |
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| `:impl/representation` | representation detail (e.g. syntax-quote yields a `list?`, not a `Cons`) |
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| `:bug` | a *known defect* (tracked bead) — not a host difference |
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## Hosting jolt on a new runtime
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1. Implement the reader + analyzer + a backend for your runtime (see the Chez port
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under `host/chez/` for a worked example).
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2. Write a ~30-line harness that, for each corpus row, evaluates `:actual` and
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`:expected` and compares by value-equality (skip `:throws` rows to an
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expect-raises check). Pseudocode:
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```
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(doseq [{:keys [suite label actual expected]} (read-edn "test/chez/corpus.edn")]
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(let [feats (profile-features [suite label])] ; from profile.edn
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(when (subset? feats my-implemented-features) ; only cases I claim to support
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(record! [suite label]
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(if (= :throws expected)
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(raises? actual)
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(value= (eval actual) (eval expected)))))))
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```
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3. Run it. Your **conformance level** is the set of feature families with no
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failures. Portable-only is the floor; each feature you implement raises it.
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The reference harness does exactly this on Chez: `host/chez/run-corpus.ss` (the
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analyzer runs on Chez → Chez runtime), with a regression floor. Run it via `make
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corpus`.
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## Maintaining the spec
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- **Add/change cases**: edit `test/chez/corpus.edn` directly, then re-source the
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answers with `regen-corpus.clj`.
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- **Re-certify**: `clojure -M test/conformance/certify.clj`. A new divergence is
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either a real bug (file it, mark the allowlist entry `:bug` + `:bead`) or a
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deliberate delta (classify it in `known-divergences.edn`).
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- **Refresh the profile**: re-run with `--profile test/conformance/profile.edn`.
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- **Re-floor the runtime gate** when parity rises (`host/chez/run-corpus.ss`).
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