nrepl-eval

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:

1. Evaluate Clojure code during development — test functions, inspect state, or run experiments against a running Clojure process.
2. Verify that edited files compile — require namespaces with :reload to pick up changes.
3. Inspect the last exception after a failed evaluation — use -e to 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 -p needed when your nREPL server is on 6064. Use -p <PORT> for a different port.
• Always use :reload when requiring namespaces to pick up file changes.
• Session is reused across invocations — defs, in-ns, and var bindings persist. Use --reset-session to 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).