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
• 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
• Built on parinfer (pure JS, no native dependencies)

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 [email protected]