AI Prompts for Clojure & Electric Clojure v3 / Cursor Rules

AI coding guidelines for Clojure & Electric Clojure v3 (ala .cursor/rules) to help LLMs write idiomatic Clojure code when working on large projects.

These guidelines were derived by Claude Sonnet 3.7 by reading various books & Clojure repositories with some manual intervention to clarify contradictions.

Goal

As we enter the 4th Industrial Revolution, I hope that this repo can be a starting point to bring idiomatic Clojure to AI models.

Currently the files are quite long and could be more concise, but I would rather err on the side of verbosity.

How to Use These Clojure Prompts

If you're using Cursor, you'll want to add these *.mdc files under .cursor/rules in your workspace. Here's how:

1. cd ~/my-project
2. cd .cursor/rules or make .cursor/rules dir
3. git clone git@github.com:theronic/clojure-prompts.git clojure (now you'll have .cursor/rules/clojure/*.mdc)
4. Update your .cursor/rules/README.md and mention something like alongside your other architecture rules:

## Language-Specific Rules

- **[Clojure Rules](./clojure/clojure-rules.mdc)**: Clojure development guidelines
- **[Electric Clojure v3 Rules](./clojure/electric-clojure-v3.mdc)**: Electric Clojure v3 development guidelines. Electric clojure namespaces are usually `*.cljc` files and `(:require [hyperfiddle.electric3 :as e])` in top-level namespace.

If you're using Claude Code, you'll want to mention the same (with corrected paths) in CLAUDE.md.

A git submodule may be more convenient to keep up-to-date on the latest prompts. I'll add instructions once I figure out a convenient workflow.

Personal Conventions

• The ! prefix notation for references like atoms, e.g. (def !state (atom {})) is my preference because then (swap! !state conj ...) looks right, as well as @!state to distinguish from values.
• The ! suffix notation for effectful functions like (defn save-user! [conn user-data] ...) warns the user that this function is not pure.

Knowledge Was Derived from these Sources:

• Elements of Clojure by Zachary Tellman.
• The Joy of Clojure (2nd Edition) by Michael Fogus and Chris Houser
• Electric Clojure v3 Tutorials (as of 2025-03-23) by Hyperfiddle.

Elements of Clojure is the book I would have written about Clojure, if I could. All hail, Tellman.

WARNING: Electric Clojure v3 is in active development & guidelines will have mistakes

I added guidelines for Electric v3 because models with a knowledge cut-off in 2024 tend to output Electric v2 code even when I ask for v3 code.

Electric Clojure v3 is being actively developed and some of these guidelines are almost certainly wrong – sorry about that! Happy to fix as discovered :).

PRs welcome if they improve outcomes.