Basilisp nREPL

Bridges Anthropic's Model Control Protocol with Basilisp's nREPL server, enabling direct execution of Basilisp code, documentation retrieval, namespace exploration, and Python interoperability.

Installation Instructions

README: https://github.com/cat-state/nrepl-mcp

Basilisp nREPL MCP Bridge

This project provides a bridge between Anthropic's Model Control Protocol (MCP) and Basilisp's nREPL server, allowing Claude Code to interact directly with a Basilisp REPL. Actually, it should work with any nREPL, but the current prompts are Basilisp focused.

Features

• Execute code and receive pretty-printed, syntax-highlighted results
• Get documentation for symbols
• List all available namespaces
• Find all variables in a namespace
• Check nREPL server connectivity
• Basilisp: Python interop with proper syntax for attribute access and method calls
• Enhanced error reporting and formatting

Requirements

• uv
• basilisp

Usage

1. Start a Basilisp nREPL server:

   basilisp nrepl-server --port 36915
   

2. Add the MCP bridge to Claude Code:

   claude mcp add /home/a/subjective/snr/basilisp_mcp_bridge.py
   

3. Connect with Claude and use the available tools:

   • eval_code(code) - Evaluate Basilisp code
   • get_docs(symbol) - Get documentation for a symbol
   • find_namespace_vars(namespace) - List variables in a namespace
   • list_namespaces() - List all available namespaces
   • check_connection() - Verify nREPL connectivity

Python Interop Examples

;; Import a module
(import [math :as math])

;; Access an attribute
(. math -pi)  ;; or (.-pi math)

;; Call a method
(.sin math 0)

;; Create Python data structures
#py{"key" "value"}

Future Improvements

• Implement a proper bencode parser (beyond regex)
• Add session management for multiple REPLs
• Add auto-completion support