Interactive Common Lisp

A modern REPL experience with syntax highlighting, auto-completion, data visualization, and AI integration

Works with SBCL, CCL, ECL, ABCL, Clasp, and Roswell

CI Release License: MIT
↓ Download View Source 
$ icl
;; ICL - Interactive Common Lisp
CL-USER> (defun greet (name)
           (format nil "Hello, ~A!" name))
=> GREET
CL-USER> (greet "Lisper")
=> "Hello, Lisper!"
CL-USER> ▌

Three Ways to REPL

Use ICL however you prefer

⌨

Terminal

Terminal Demo

Syntax highlighting, paredit, tab completion, and interactive object inspector

icl
🌐

Browser

Browser Demo

Package browser, symbol inspector, class hierarchies, data visualization, and live notebooks

icl -b
📝

Emacs

Emacs Demo

Integrates with SLY/SLIME for synchronized browser visualizations

M-x icl

Notebooks

Jupyter-style notebooks in the browser, with the full ICL editor in every cell — paredit, completion, and click-to-inspect. Rich outputs render charts, diagrams, and interactive pivot tables; reactive widgets re-run cells on change; and it all works offline.

,notebook analysis.iclnb
Notebook Demo

Flame Graph Profiling

Profile any expression and explore the results in an interactive Speedscope visualization. Identify performance bottlenecks with Time Order, Left Heavy, and Sandwich views.

,flame (my-expensive-function)
Flame Graph Demo

Features

🎨

Syntax Highlighting

Colorized input with matching parentheses

🔧

Paredit Mode

Structural editing with balanced parens

📊

Data Visualization

Hash tables, classes, Vega-Lite, Mermaid

📓

Notebooks

Live cells with the full ICL editor, rich output, and KaTeX math

🔥

Flame Graphs

Interactive Speedscope profiling

🤖

AI Integration

Explain code with Claude, Gemini, Codex

🔍

Object Inspector

TUI for exploring complex objects

📦

Multiple Lisps

SBCL, CCL, ECL, ABCL, Clasp, Roswell

🔬

Disassembly View

Visualize function machine code

Installation

Pre-built Binaries

Download RPM, DEB, or Windows installers

Download →

Roswell

ros install atgreen/icl

Build from Source

git clone https://github.com/atgreen/icl.git
cd icl && ocicl install && make