By name: nrepl-eval description: Evaluate Clojure code via nREPL using the standalone tools/nrepl-eval.mjs CLI tool.
nREPL Eval
Evaluate Clojure (or ClojureScript) code via a running nREPL server using
tools/nrepl-eval.mjs — a standalone CLI application.
Session state (defs, in-ns, etc.) persists across invocations via a stored session ID, so you can build up state incrementally.
Usage
node tools/nrepl-eval.mjs [options] [<code>]
The tool is also executable directly:
./tools/nrepl-eval.mjs [options] [<code>]
Options
| Flag | Description | Default |
|---|---|---|
-p, --port PORT |
nREPL server port | 6064 |
-H, --host HOST |
nREPL server host | 127.0.0.1 |
-t, --timeout MS |
Timeout in milliseconds | 120000 |
--reset-session |
Discard stored session and start fresh | — |
-e, --last-error |
Evaluate *e to retrieve the last exception |
— |
-h, --help |
Show help message | — |
When to Use
Use this tool when you need to:
- Evaluate Clojure code during development — test functions, inspect state, or run experiments against a running Clojure process.
- Verify that edited files compile — require namespaces with
:reloadto pick up changes. - Inspect the last exception after a failed evaluation — use
-eto print the error stored in*e.
Workflow
1. Session management
Sessions are persisted to /tmp/penpot-nrepl-session-<host>-<port>. State
carries across calls automatically:
./tools/nrepl-eval.mjs '(def x 42)'
./tools/nrepl-eval.mjs 'x'
# => 42
Reset the session to start fresh:
./tools/nrepl-eval.mjs --reset-session '(def x 0)'
2. Evaluate code
Single expression (inline) — uses default port 6064:
./tools/nrepl-eval.mjs '(+ 1 2 3)'
Multiple expressions via heredoc (recommended — avoids escaping issues):
./tools/nrepl-eval.mjs <<'EOF'
(def x 10)
(+ x 20)
EOF
Override with a different port:
./tools/nrepl-eval.mjs -p 7888 '(+ 1 2 3)'
3. Inspect last exception
After code throws an error, retrieve the full exception details:
./tools/nrepl-eval.mjs -e
Common Patterns
Require a namespace with reload:
./tools/nrepl-eval.mjs "(require '[my.namespace :as ns] :reload)"
Test a function:
./tools/nrepl-eval.mjs "(ns/my-function arg1 arg2)"
Long-running operation with custom timeout:
./tools/nrepl-eval.mjs -t 300000 "(long-running-fn)"
Key Principles
- Default port is 6064 — just pass code directly, no
-pneeded when your nREPL server is on 6064. Use-p <PORT>for a different port. - Always use
:reloadwhen requiring namespaces to pick up file changes. - Session is reused across invocations — defs, in-ns, and var bindings
persist. Use
--reset-sessionto clear. - Do not start any server — the tool connects to an existing nREPL server, it is not the agent's responsibility to start the nREPL server (assume the server is already running on the specified port).