realgenekim

After watching the Clojure/conj 2025 talk on ECA, I was inspired to try using the clojure-lsp plugin. I stumbled upon the cclsp MCP server, which seemed like the ideal way to use this with Claude Code.

Enclosed below are all the instructions necessary to get them both up and running.

My high-level impressions:

• Claude Code seems to love having cclsp around when doing large refactorings -- having done several, some with and some without, those with cclsp and clojure-lsp seem to go more smoothly

I'd love to hear your thoughts!

realgenekim

S-Expression Guard MCP Server

Problem Statement

LLMs frequently emit malformed S-expressions (unbalanced ()[]{}) when generating Clojure/EDN/Lisp code. Post-hoc “repair” is surprisingly difficult. Saving source code files with balancing errors, or streaming them to nREPL/compilers, wastes time and relies on imbalance detection after the tokens are generated.

What if we could prevent these types of error by creating a tool (stateless, stack-based, cursor-aware) for LLMs to use to help them write perfectly balanced S-expression. Ideally while minimizing latency, round-trips, total time required to generate code, and without any MCP server-side state.

Current LLMs are inherently auto-regressive auto-completers, which makes them inherently bad at the problem of closing S-expressions -- they don’t have anything resemblig a “stack” for them to store state (e.g., I just emitted an open parenthesis, and here’s an open bracket. I want to close the form — now what?). Nor does it have an equivalent of a “find

realgenekim

Map Key Errors in Clojure and Python: A Silent Bug Category

Why This Matters

I've been compiling this document for a couple of weeks, with the intent of publishing it, to at least advertise this problem I've been struggling with. One that has been bothering me enough where I've done a ton of little experiments to see if I can ameliorate it, even by a little!

Then just now, I was talking with my friend Scott Prugh who was just complaining about something in Python, and he was lamenting how he wanted to do things in C#. I asked him why, and he was complaining about the same problem that I've been having!

The problem: LLMs will often hallucinate map keys that don't exist. He and I commiserated about how we both spent hours trying to hunt down a problem that would have been solved if there were a data structure more like a class or a struct in C, where you could generate an immediate error if trying to get or set a value that doesn't actually exist.

realgenekim

# Java proxy configuration for local proxy shim
# Source this file before running Maven/Gradle/Clojure builds
#
# Usage: . ./.proxy-java-shim.env && mvn test

export JAVA_TOOL_OPTIONS="-Dhttp.proxyHost=127.0.0.1 -Dhttp.proxyPort=15080 -Dhttps.proxyHost=127.0.0.1 -Dhttps.proxyPort=15080"
export MAVEN_OPTS="$JAVA_TOOL_OPTIONS"

realgenekim

Fantastic—here’s a compact, copy‑pasteable doc you can hand to tech‑leader participants. Every dataset below is (a) free, (b) downloadable for local/offline analysis on a dev‑class laptop, and (c) has a clear “what it’s good for.” I include at least one option for each topic you asked for, plus a bonus section with public backlogs/tickets/incident datasets.

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Vibe‑Coding Workshop Datasets (Local/Offline Friendly)

1) Jira / Backlog Data

Primary (recommended): The Public Jira Dataset (anonymized, 2025 release)

realgenekim

⏺ The instructions for retrieving Claude Code prompts are in /Users/genekim/src.local/mdparse/docs/claude-code-logs.md. Key locations:

Primary data storage:

• ~/.claude/projects/ - Project-specific sessions as JSONL files
• ~/.claude.json - Session index and configuration

To find your prompts:

List your Claude projects

ls -la ~/.claude/projects/

realgenekim

expo-av Sound Class Workaround for ClojureScript/React Native

Problem Discovery

When trying to use expo-av’s Audio.Sound class in a ClojureScript React Native app (using shadow-cljs), we encountered a persistent error:

TypeError: Cannot read property ‘prototype’ of undefined

This error occurred when trying to:

realgenekim

nREPL Client Script (nrepl.clj)

A fast Babashka script for interacting with the running nREPL server. Located at server/nrepl.clj.

Usage

The script automatically reads the port from .nrepl-port file.

Command line argument (fastest for one-off commands):

./nrepl.clj '(+ 1 2 3)'
./nrepl.clj '(require '\''[podcast.db :as db]) (count (db/get-recent-episodes 10))'

realgenekim

{:paths ["src"]
 :deps  {org.clojure/clojure      {:mvn/version "1.11.1"}
         clj-python/libpython-clj {:mvn/version "2.026"}}
 
 :aliases
 {:dev {:jvm-opts ["--enable-native-access=ALL-UNNAMED"]}}}

realgenekim

./forms_inline.cljc:

(ns electric-tutorial.forms-inline ; used in form_explainer
  (:require #?(:clj [datascript.core :as d])
            [hyperfiddle.electric3 :as e]
            [hyperfiddle.electric-dom3 :as dom]
            [hyperfiddle.electric-forms3 :as forms :refer
             [Input! Checkbox! Checkbox* Form! Service try-ok effects*]]
            [dustingetz.trivial-datascript-form :refer
             [#?(:clj ensure-conn!) #?(:clj transact-unreliable)]]))