simon/jolt

Yogthos d33277c0b2 REPL fixes + an nREPL server for editor-connected dev

The line REPL was broken (read-line called nil — the __stdin-read-line host seam
the clojure.core *in* reader drives was never implemented on Chez) and didn't
load the project, so (require '[some.lib]) failed. Now:

- __stdin-read-line reads a line from stdin (get-line); read-line / read / the
  REPL work.
- repl resolves the project first (deps on the roots, native libs loaded), so
  libraries are available — same context a run gets.
- jolt.nrepl: a jolt-native nREPL server (bencode over a loopback jolt.ffi
  socket) speaking the real protocol — clone / describe / eval / load-file /
  close, with stdout capture, :ns-scoped eval (in-ns; binding *ns* doesn't drive
  load-string resolution here), and real error text. 'joltc nrepl [port]' applies
  the project then serves; writes .nrepl-port. Editors (CIDER/Calva/Cursive)
  connect and develop live; project libraries load in the session.
- ex-message returns nil for raw Chez conditions, so jolt.host/condition-message
  exposes the condition text; the REPL and nREPL surface it instead of an opaque
  #<compound condition>.

Why native, not real nREPL: nrepl.server is welded to java.util.concurrent
executors, two compiled Java helper classes, a DynamicClassLoader, Compiler
internals and a JVMTI agent — not faithfully shimmable. The wire protocol, which
is what clients depend on, is small and implemented directly.

Runtime .ss + jolt-core, no re-mint. Full gate green.

2026-06-22 15:18:52 -04:00

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Building and dependencies

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

Running

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:

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):

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 [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:

{:paths ["src"]
 :deps {weavejester/medley {:git/url "https://github.com/weavejester/medley"
                            :git/sha "<full-sha>"}
        my/helpers          {:local/root "../helpers"}}}

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 for the design rationale.

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