jolt/docs/building-and-deps.md

Building and dependencies

How to build Jolt from source and how to pull Clojure libraries into a project.

Building

git clone https://github.com/jolt-lang/jolt.git
cd jolt
git submodule update --init   # vendor/sci (used by the SCI bootstrap tests)
jpm build

This produces two executables under build/:

• jolt — the runtime: REPL, file/expr runner, nREPL server. The whole .clj standard library (clojure.string/set/walk/edn/zip, jolt.http/ interop/shell/nrepl) is baked into this binary at build time, so it loads from any directory — the build artifact is self-contained. (clojure.core is built into the runtime in Janet and auto-referred, so it's always available.)
• jolt-deps — a separate tool that resolves a deps.edn (see below). It sits beside the runtime the way jpm sits beside janet; the runtime itself knows nothing about deps.edn.

Needs jpm and a recent Janet — developed and CI-tested against 1.41. The futures and core.async layers use Janet's threaded ev/ channels (ev/thread, ev/thread-chan), so older Janets may not run the full suite.

jpm build doesn't always notice source changes; run jpm clean && jpm build after editing src/ to be sure the binaries are current. jpm test runs against the source directly, so it never goes stale.

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 baked into the binary — that's how clojure.string and friends resolve when you run the binary outside the source tree.

So you can point Jolt at a directory of Clojure source with no deps machinery at all:

JOLT_PATH=/path/to/lib/src build/jolt myfile.clj

Dependencies via deps.edn

jolt-deps reads a deps.edn in the current directory, fetches its dependencies, and runs jolt with the resolved source directories on JOLT_PATH.

jolt-deps path             # print the resolved roots (':'-joined)
jolt-deps run FILE [args]  # resolve, then run `jolt FILE …`
jolt-deps repl             # resolve, then start a REPL
jolt-deps -e EXPR [args]   # resolve, then evaluate EXPR

jolt-deps launches the jolt binary it finds on PATH (override with $JOLT_BIN).

Example deps.edn:

{:paths ["src"]
 :deps {weavejester/medley {:git/url "https://github.com/weavejester/medley"
                            :git/tag "1.0.0"}
        my/helpers          {:local/root "../helpers"}}}

jolt-deps run -m myapp.main

What's supported

• git deps — {:git/url … :git/tag …} or {:git/url … :git/sha …} (use a full SHA; git fetch can't resolve a short one). 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.

Resolution reuses jpm's git fetch and cache (a dependency is cloned once into jpm_tree/.cache and reused). Resolved roots are cached on a hash of deps.edn, so an unchanged deps.edn doesn't re-fetch.

What's not

• No Maven. :mvn/version deps are ignored — 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.

Bundling into one file

jolt uberscript OUT.clj -m NS (or jolt-deps uberscript …, which resolves deps first) bundles NS and every namespace it requires — your code plus its dependencies — into a single .clj in dependency order, ending with a call to NS/-main. The result runs on a plain jolt with no JOLT_PATH, no deps fetched, and no jpm:

jolt-deps uberscript app.clj -m myapp.main
jolt app.clj arg1 arg2

See tools-deps.md for the design rationale.