# lem-project/lem

General-purpose editor/IDE with high expansibility in Common Lisp

Repository: https://github.com/lem-project/lem
Canonical: https://ross.abutalabs.com/products/lem
Homepage: http://lem-project.github.io/
Language: Common Lisp
License: MIT
License Family: permissive
Topics: common-lisp, editor, text-editor
Last push: 2026-08-12T12:56:41+00:00

## Health v2 (maintenance only)
Score: 66/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 97, release rhythm 8, longevity 100
- inputs: {"age_days": 4046, "days_push": 21, "days_rel": 414, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3032, forks 255 (observed 2026-08-28T04:07:38.981261+00:00)

## What it is
Lem is a general-purpose text editor and IDE written in and extensible with Common Lisp, offering Emacs/Vim-style keyboard workflows, built-in LSP support for many languages, and a full Common Lisp REPL and debugger. It runs as a terminal (ncurses) application or GUI (SDL2/webview) and can be extended live while running.

## Use cases
- edit code with an Emacs-like keyboard-driven editor
- develop Common Lisp with a REPL and interactive debugger
- use LSP-based code intelligence across many languages
- extend an editor live in Common Lisp
- run a lightweight terminal IDE over ssh
- use a GUI editor with mouse support and color themes

## When to choose
- you want an Emacs-like editor extensible in Common Lisp
- you do Common Lisp development and want an integrated REPL and debugger
- you need a fast terminal editor with LSP support
- you want one editor that works in terminal, ncurses, SDL2, and webview modes

## When to avoid
- you need a large plugin ecosystem like VS Code's marketplace
- you prefer mouse-first GUI IDEs like JetBrains products
- you don't want to learn Lisp for customization
- you need mobile or web-based editing

## Facets
- artifact type: application
- maturity: active
- function: editor, developer-tools, gui, cli
- domain: text-editors, developer-tools, programming-languages
- platform: windows, cross-platform, cli
- tags: common-lisp, lsp, emacs-alternative, extensible-editor, repl, ncurses, sdl2, webview, paredit, lisp-ide, linux, macos, desktop

## Member repositories
- lem-project/lem (main) score 66

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:38.981261+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:29:47.554121+00:00, confidence not recorded.
  - readme: https://github.com/lem-project/lem (fetched 2026-08-28T04:07:38.981261+00:00, sha 0cee27a9de0b)
  - homepage: http://lem-project.github.io/ (fetched 2026-08-29T09:44:36.021875+00:00, sha 733d825f78b0)
- Data as of 2026-08-30T08:39:29.467469+00:00.