jolt/README.md
Yogthos b460875772 Add an install script for the prebuilt joltc binary
install (root) downloads the self-contained joltc release asset for the host
platform, verifies its sha256, and drops the binary in /usr/local/bin (--dir /
--version override). Resolves the latest release via the GitHub API, clears the
macOS quarantine flag, and backs up an existing joltc. Modeled on babashka's
installer. README gets a one-line curl|bash install.
2026-07-01 16:38:43 -04:00

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# Jolt
[![tests](https://github.com/jolt-lang/jolt/actions/workflows/tests.yml/badge.svg)](https://github.com/jolt-lang/jolt/actions/workflows/tests.yml)
A Clojure implementation on [Chez Scheme](https://cisco.github.io/ChezScheme/).
Jolt reads Clojure source, analyzes it to a host-neutral IR, emits Scheme, and
runs it on Chez. The compiler is self-hosted: it is written in Clojure
(`jolt-core/`) and compiles itself. It ships a Clojure-compatible standard library.
## Install
Grab the self-contained `joltc` binary (Linux/macOS) — it bundles the runtime,
compiler, and standard library, so there is nothing else to install:
```bash
curl -sL https://raw.githubusercontent.com/jolt-lang/jolt/main/install | bash
```
It installs to `/usr/local/bin` by default; `--dir <dir>` and `--version <v>`
override that. Then `joltc -e '(+ 1 2)'`. To run from source instead (needs Chez),
see [Build](#build).
## Requirements
Only [Chez Scheme](https://cisco.github.io/ChezScheme/) (the gate invokes it as
`chez`). The conformance gate additionally uses Clojure on the JVM as an oracle,
but running jolt does not.
## Build
There is no build step. The bootstrap seed (`host/chez/seed/{prelude,image}.ss`)
is checked in, so a fresh clone runs immediately:
```bash
git clone --recurse-submodules https://github.com/jolt-lang/jolt.git
cd jolt
bin/joltc -e '(+ 1 2)' # => 3
```
After changing a compiler source — the reader (`host/chez/reader.ss`), the
analyzer/IR/backend (`jolt-core/jolt/*.clj`), or the `clojure.core` overlay
(`jolt-core/clojure/core/*.clj`) — re-mint the seed:
```bash
make remint # iterates host/chez/bootstrap.ss to a byte-fixpoint
```
## Run
```bash
bin/joltc -e EXPR # evaluate a Clojure expression and print the result
```
```bash
$ bin/joltc -e '(->> (range 10) (filter even?) (map (fn [x] (* x x))) (reduce +))'
120
$ bin/joltc -e '(/ 1 2)'
1/2
```
## REPL and editor integration
```bash
bin/joltc repl # a line REPL with the project's deps loaded
bin/joltc --nrepl-server [port] # an nREPL server (default 7888) for editors
```
Both resolve the `deps.edn` in the current directory first, so the project's
source roots and native libraries are loaded — `(require '[my.ns])` works live.
`--nrepl-server` writes a `.nrepl-port` file in the project dir, so CIDER / Calva / Cursive
auto-detect the port; override it with the argument or `JOLT_NREPL_PORT`.
The server runs in dev mode — calls deref their var, so redefining a function
takes effect on the next call without restarting the process. The built-in
handler speaks `clone`/`describe`/`eval`/`load-file`/`close`; heavier ops
(sessions, interruptible eval, completion) are added as nREPL middleware listed
in `deps.edn` under `:nrepl/middleware`.
```clojure
;; from your editor, against the running process:
(require '[myapp.core :as app])
(app/start!) ; bring the app up
;; edit a handler, re-evaluate the defn — the running app sees it, no restart
(app/stop!)
```
## Compile a binary
`bin/joltc build` ahead-of-time compiles a project into a single self-contained
executable — the runtime, `clojure.core`, the standard library, the app, and its
`deps.edn` dependencies are linked in, so the result needs no Chez install, no
JVM, and no source on disk to run.
```bash
bin/joltc build -m myapp.core -o myapp # compile myapp.core's -main into ./myapp
./myapp arg1 arg2 # runs anywhere; args reach -main
```
Modes trade dynamism for speed: the default (release) build uses the proven code
generator; `--opt` also runs the inference + inlining + scalar-replacement passes
over the closed-world program; `--dev` is unoptimized.
Two opt-in closed-world flags cut dispatch cost and binary size:
```bash
bin/joltc build -m myapp.core --direct-link # app->app calls bind directly (no var lookup)
bin/joltc build -m myapp.core --tree-shake # ship only code reachable from -main
```
`--tree-shake` walks the call graph across your app, its libraries, and
`clojure.core`, drops everything unreachable from `-main` (and the compiler itself
when the app never `eval`s), and typically removes 12 MB. It stays sound by bailing
out — keeping everything, and reporting which library is responsible — when reachable
code resolves vars by name at runtime (`eval`/`resolve`/`ns-resolve`/…). See
[docs/tools-deps.md](docs/tools-deps.md) and `docs/rfc/0007`.
This needs Chez's kernel development files (`libkernel.a`, `scheme.h`) and a C
compiler. They come with a from-source Chez install; a distro `chezscheme`
package ships only the runtime, so `build` won't link a binary there.
RFC 0007 (`docs/rfc/`) covers the design and the three-mode model.
## Standalone joltc binary
`make` builds joltc itself into a single self-contained native binary — the
runtime, compiler, `jolt-core`/`stdlib` source, and the Chez boots are baked in,
so the result runs and `build`s jolt apps on a machine with neither Chez nor a C
compiler. Build it on a host that *does* have both.
```bash
make joltc-release # => target/release/joltc (optimize-level 3, compressed)
make joltc-debug # => target/debug/joltc (optimize-level 0, inspector + debug info)
make joltc # re-mint the seed first, then both
```
`make joltc` re-mints the seed so the embedded compiler image is current before
linking; use `joltc-release`/`joltc-debug` directly to skip that when the seed is
already minted. Like `build`, both require Chez's kernel development files
(`libkernel.a`, `scheme.h`) and a C compiler.
## Architecture
A small Chez runtime (`host/chez/*.ss`: value model, persistent collections, seqs,
vars/namespaces, host interop) hosts a portable Clojure overlay split across two
source roots by *when* they load:
- **`jolt-core/`** is baked into the seed — the compiler (`jolt-core/jolt/`:
reader/analyzer/IR/backend, plus `jolt.main`/`jolt.deps`) and `clojure.core` in
dependency-ordered tiers (`jolt-core/clojure/core/NN-*.clj`). Changing anything
here means re-minting the seed.
- **`stdlib/`** loads lazily at runtime off the source roots — the rest of the
standard library (`clojure.string`/`set`/`walk`/`edn`/`pprint`/…) plus the
`jolt.ffi` host library. Editing these needs no re-mint.
`bin/joltc` loads the checked-in seed and the spine, then compiles and evaluates on
Chez (read → analyze → IR → emit → eval). `host/chez/bootstrap.ss` rebuilds that
seed from source on pure Chez; the build is a self-hosting fixpoint (a rebuild
reproduces the checked-in seed byte-for-byte).
## Differences from Clojure
Jolt targets Clojure semantics but runs on Chez, not the JVM. Most portable
Clojure runs unchanged — persistent collections (32-way-trie vectors, HAMT
maps/sets), the numeric tower (exact integers, bignums, ratios, doubles), lazy
and infinite sequences, transducers, destructuring, multimethods with
hierarchies, protocols/records (`deftype`/`defrecord`/`reify`/`extend-protocol`),
metadata, namespaces, atoms, `future`/`promise`/`agent`/`pmap`,
`clojure.core.async`, runtime `eval`/`load-string`/`defmacro`, and the full
reader (`#()`, `#_`, `#?`, tagged literals, `#"…"`) all behave as on the JVM.
`=` is category-aware (`(= 3 3.0)``false`) and `==` is value-equality, as in
Clojure. The genuine divergences:
- **No JVM, no Java interop.** No reflection, no `gen-class`/`proxy`. Interop
syntax (`Class.`, `Class/static`, `.method`) resolves only against a shimmed
subset of the `java.*` standard library; a class token is a name, not a loaded
class. See [docs/host-interop.md](docs/host-interop.md). To call C libraries
directly, use the `jolt.ffi` foreign-function interface (how the db and
http-client libraries bind SQLite/libpq and sockets/OpenSSL/zlib).
- **No `BigDecimal`.** `decimal?` is always false and there is no `M` literal;
the rest of the numeric tower matches the JVM.
- **No STM.** No `ref`/`dosync`/`alter`/`commute` — coordinated shared state uses
atoms (per-atom mutex, JVM-style CAS). The concurrency primitives above are
otherwise present and run on a shared heap.
- **Regex engine.** Patterns compile through
[irregex](https://github.com/ashinn/irregex) (vendored), not
`java.util.regex`; common patterns work, Java-specific features can differ.
- **Coverage.** `clojure.core` is implemented function by function against the
JVM-sourced conformance corpus — broad but not total; a namespace can load with
most functions working and a few not yet implemented.
## Test
```bash
make test # the full gate
make corpus # conformance corpus vs the JVM-sourced spec
make unit # host-specific unit cases
make selfhost # bootstrap fixpoint (rebuild == checked-in seed)
make smoke # bin/joltc CLI smoke
make sci # load borkdude/sci's source through joltc (compat stress)
make ffi # HTTP-server GC-safety + http-client temp paths
make transient # transient mutation + linear-time builds
make certify # JVM oracle (skips if clojure is absent)
```
The conformance corpus (`test/chez/corpus.edn`) is a host-neutral language spec
whose expected values are sourced from reference JVM Clojure. See
[test/conformance/SPEC.md](test/conformance/SPEC.md).
## License
[Eclipse Public License 2.0](https://www.eclipse.org/legal/epl-2.0/)