pi-clojure

A set of Clojure development tools implemented in pure JavaScript for the pi-coding-agent.

Why this project?

Existing solutions for Clojure evaluation in AI coding agents (e.g., clojure-mcp, clojure-mcp-light) either:

• Introduce the overhead of MCP (Model Context Protocol) as an additional communication layer
• Rely on CLI tools for execution, which adds process spawn overhead

These approaches can create performance bottlenecks, especially on resource-constrained systems. Additionally, MCP introduces complexity in setup and maintenance.

This project takes a different approach: implementing Clojure evaluation as native pi tools that communicate directly with nREPL via TCP sockets. This eliminates any middleware layer, providing:

• Zero overhead: Direct tool invocation without MCP protocol translation
• Direct execution: Code evaluated directly via nREPL without CLI process spawning overhead
• Simpler architecture: No external dependencies or protocol adapters

Installation

pi install npm:pi-clojure

Tools

Tool	Description
clojure_eval	Evaluates Clojure code via nREPL
clojure_find_nrepl_port	Finds nREPL port by checking port files or trying default ports
clojure_paren_repair	Fixes unbalanced delimiters in Clojure/ClojureScript/Babashka code. Standalone — no nREPL required.

clojure_eval

Evaluates Clojure code via nREPL.

Note: Requires an existing nREPL connection. Use clojure_find_nrepl_port to find a running nREPL, or start one manually.

Features

• Evaluates Clojure code via nREPL protocol
• Discovers nREPL endpoints on common ports
• Supports custom namespaces
• Handles stdout/stderr output

Configuration

Default nREPL Ports

The extension auto-detects nREPL on these ports:

• 7888, 1666, 50505, 58885, 63333, 7889

Parameters

Parameter	Type	Description
code	string	Clojure code to evaluate
port	number	nREPL port (required)
host	string	nREPL host (default: localhost)
ns	string	Target namespace

Usage

Start nREPL in your Clojure project:

clj -M:nrepl

Then use the clojure_eval tool in pi-coding-agent to evaluate code.

clojure_find_nrepl_port

Finds the nREPL port by checking for port files in the current directory or trying common default ports. Validates the connection by evaluating (+ 1 1).

Features

• Checks for common nREPL port files:
  • .nrepl-port
  • nrepl-port
  • .shadow-cljs/nrepl.port
  • .cider-nrepl.port
• Falls back to default ports: 7888, 1666, 50505, 58885, 63333, 7889
• Validates by connecting and evaluating (+ 1 1)

Parameters

None.

Usage

;; Find the nREPL port
(clojure_find_nrepl_port {})
;; Returns: Found nREPL port 7888 at localhost:7888

clojure_paren_repair

Fixes unbalanced delimiters in Clojure, ClojureScript, and Babashka code using parinfer. Standalone tool — does not require nREPL or any running process.

Works with all Clojure-type source files: .clj, .cljs, .cljc, .bb

Features

• Works with Clojure, ClojureScript, and Babashka
• Detects unbalanced (, [, {, ), ], }
• Auto-inserts missing closing delimiters
• Handles strings, comments, and escape sequences
• Pure JavaScript implementation (no native deps)

Parameters

Parameter	Type	Description
code	string	Clojure code with potentially unbalanced delimiters
check	boolean	(optional) Only check if balanced, don't fix

Usage

;; Fix unbalanced delimiters
(clojure_paren_repair { code: "(defn foo [x]" })
;; Returns: Fixed delimiters:
;; ```clojure
;; (defn foo [x])
;; ```

;; Check if balanced (without fixing)
(clojure_paren_repair { code: "(defn foo [x])", check: true })
;; Returns: Code has balanced delimiters

Examples

Input	Output
(defn foo [x]	(defn foo [x])
((foo [bar] [baz]	((foo [bar] [baz]))
(defn foo [x y] x)	(defn foo [x y] x) (no change)

License

EPL-2.0

Copyright © 2026-present Marko Kocic marko@euptera.com