jolt/docs/building-and-deps.md
Yogthos 823bc5bcc6 cli: rename nrepl command to --nrepl-server flag
Match babashka's spelling: the nREPL server now starts with
`bin/joltc --nrepl-server [port]` instead of `bin/joltc nrepl`. Port
parsing and JOLT_NREPL_PORT are unchanged.

Also wire up --help/-h to print usage (previously only the no-arg
invocation did), and fix the usage listing to show the real flag.
Smoke now asserts --help mentions --nrepl-server. Docs updated to match.
2026-06-28 17:26:03 -04:00

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4.6 KiB
Markdown

# Building and dependencies
How to run Jolt from source and how to pull Clojure libraries into a project.
## Running
```bash
git clone https://github.com/jolt-lang/jolt.git
cd jolt
git submodule update --init # vendor/sci (used by the SCI bootstrap tests)
bin/joltc -e '(println "hello")'
```
There is **no build step**. `bin/joltc` (`host/chez/cli.ss`) loads the
checked-in bootstrap seed (`host/chez/seed/{prelude,image}.ss`) plus the spine
and compiles+evals on Chez (read → analyze → IR → emit → eval), so a fresh
clone runs immediately. The whole `.clj` standard library
(`clojure.string`/`set`/`walk`/`edn`/`pprint`/…) and `clojure.core` are part of
the overlay, so they're always available.
`bin/joltc` is both the runtime (REPL, file/expr runner) and the dependency
front-end (`deps.edn` resolution, see below). A run with no `deps.edn` never
touches the resolver.
The bootstrap seed is **checked in**. After changing a seed 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 with
`make remint` (it iterates `host/chez/bootstrap.ss` to a byte-fixpoint), or
`make selfhost` fails. Runtime-only `host/chez/*.ss` shims don't need a re-mint.
## How namespaces are found
`(require ...)` resolves a namespace to a file by searching an ordered list of
source roots — the stdlib first, then any extra roots — trying `<ns>.clj` then
`<ns>.cljc` (dots become directories, dashes become underscores). Extra roots
come from:
- `JOLT_PATH` — a colon-separated list of directories (like a classpath), applied
at runtime;
- the `:paths` option to `init` when embedding Jolt as a library.
If a namespace isn't found on any root, the loader falls back to the stdlib in
the overlay — that's how `clojure.string` and friends resolve when you run
outside the source tree.
So you can point Jolt at a directory of Clojure source with no deps machinery at
all:
```bash
JOLT_PATH=/path/to/lib/src bin/joltc run myfile.clj
```
## Dependencies via deps.edn
`bin/joltc` reads a `deps.edn` in the current directory, fetches its
dependencies, and prepends the resolved source directories to the source roots
for the run. The CLI commands (`jolt.deps` + `jolt.main`):
```bash
bin/joltc run -m NS [args] # resolve deps.edn, load NS, call its -main
bin/joltc run FILE # resolve deps.edn, load a Clojure file
bin/joltc -M:alias [args] # run the alias's :main-opts
bin/joltc -A:alias [args] # add the alias's paths/deps, then run the rest
bin/joltc repl # start a line REPL (project deps + native libs loaded)
bin/joltc --nrepl-server [port] # start an nREPL server (default 7888) for editors
bin/joltc path # print the resolved source roots (':'-joined)
bin/joltc <task> # run a deps.edn :tasks entry
```
Example `deps.edn`:
```clojure
{:paths ["src"]
:deps {weavejester/medley {:git/url "https://github.com/weavejester/medley"
:git/sha "<full-sha>"}
my/helpers {:local/root "../helpers"}}}
```
```bash
bin/joltc run -m myapp.main
```
### What's supported
- **git deps** — `{:git/url … :git/sha …}` (use a full SHA; `git fetch` can't
resolve a short one), with an optional `:deps/root` for a subdirectory.
Transitive deps from each dependency's own `deps.edn` are resolved too.
- **local deps** — `{:local/root "../path"}`.
- The project's own `:paths` (default `["src"]`) are included.
- **aliases** — `:aliases {:dev {:extra-paths ["dev"] :extra-deps {…}
:main-opts ["-e" "…"]}}`, selected with `-A:dev` (or several: `-A:dev:test`).
`:extra-paths`/`:extra-deps` accumulate across selected aliases;
`:main-opts` is last-wins and runs via `-M:alias`.
- **tasks** — `:tasks {clean "rm -rf target" test {:main-opts ["-m" "…"]}}`.
A string task is a shell command; a map task runs jolt with its `:main-opts`.
Run one with `bin/joltc <taskname>`.
Resolution is breadth-first, so a top-level coordinate always beats a transitive
one for the same lib.
Git clones land in a global, sha-immutable cache shared across projects —
`$JOLT_GITLIBS`, else `~/.jolt/gitlibs`.
### What's not
- **No Maven.** `:mvn/version` deps are skipped with a warning — git and local
only.
- **Pure `clj`/`cljc` only.** A library that needs the JVM (Java interop, host
classes) or a `clojure.core` feature Jolt doesn't implement will fail to load
or fail at a call. Coverage is per-function: a namespace can load with most
functions working and a few not.
See [`tools-deps.md`](tools-deps.md) for the design rationale.