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lem-project/lem

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

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lem-project/lem has 3k+ stars and 250+ forks on GitHub, is written in Common Lisp, and was last pushed on Oct 16, 2026. Data as of . Signed-in members get hourly updates — create a free account.

Summary Information

Updated 1 hour ago
Type:ApplicationCategory(s):Editors & IDEsDeveloper Tools
Added to GitGenius on September 22nd, 2026
Created on August 5th, 2015
Open Issues & Pull Requests: 89 (+0)
GitHub issues: Enabled
Number of forks: 261
Total Stargazers: 3,060 (+0)
Total Subscribers: 70 (+0)

Repository Insights (GitGenius)

Median issue/PR response: 29.7 hours
Mean response time: 82.7 days
90th percentile: 301.1 days
Tracked items: 287

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Maintainer activity

2 people did triage or write work on this repository in the last 12 months.

Counts unlabeled, assigned, unassigned, milestoned, demilestoned, locked, unlocked over the last 12 months. These are issue and pull request events that require triage or write permission. Commits and code review are not counted. labeled and renamed are excluded because GitHub issue forms record the issue author as the actor. Figures from October 18, 2026. This count is not comparable across projects: each project's automation decides which of these events a person emits. How this is counted.

How this project is maintained

Roughly one issue in three opened in the past year never receives a reply. 82% of open issues come from outside the core team, so the backlog reflects real-world use rather than internal planning. 65% of tracked open issues have had no activity in three months, so the open count overstates what is actively being worked. Only 37% of issues opened in the past year have been closed. Three people close 78% of everything that gets resolved.

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Issue Activity (beta)

Open issues: 74
New in 7 days: 0
Closed in 7 days: 1
Avg open age: 349 days
Stale 30+ days: 63
Stale 90+ days: 49

Recent activity

Opened in 7 days: 0
Closed in 7 days: 1
Comments in 7 days: 0
Events in 7 days: 0

Top labels

  • stale (112)
  • enhancement (48)
  • bug (31)
  • Feature (30)
  • Feature: Lisp Mode (20)
  • good-first-issue (20)
  • waiting response (11)
  • sdl2 (8)

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Detailed Description

Lem is a general-purpose text editor and IDE written in Common Lisp with high extensibility.

The tool addresses the problem of maintaining developer flow while testing code by bringing the distance between editing and execution as close to possible. Its approach centers on instantly reflecting executed code inline and visualizing running code in real time, allowing developers to see program results without leaving the editor. The editor is fully customizable, with extensions taking effect immediately as they are written. Lem offers multiple interface options including terminal, webview, and SDL2 versions to suit different workflows.

Lem suits developers who work in Common Lisp or want a highly customizable editor environment where live feedback during development is a priority. It is particularly valuable for those who value immediate visual feedback on code execution and prefer building their own editor experience through extensions rather than adopting a pre-configured tool. The project explicitly pursues its own unique approach rather than imitating Emacs or Vim, making it a distinct choice for developers seeking an alternative philosophy.

The project maintains active development with nightly builds available and supports installation through multiple channels including Nix, Docker, and direct builds for Linux, macOS, and Windows. The tool provides documentation targeting beginners, extension developers, and core developers, and aims to deliver a comfortable environment out of the box with an intuitive and consistent API for extensions.