GitHub - lem-project/lem: General-purpose editor/IDE with high expansibility in Common Lisp

Lem: Editor Modules

After installing lem, you can start developing and extend the editor while it runs.

Install

nightly build

Tested on Ubuntu 24.04 and macOS(apple silicon).

https://github.com/lem-project/lem/releases/tag/nightly-latest

Nix

$ nix profile add github:lem-project/lem#
$ nix profile add github:lem-project/lem#lem-ncurses
$ nix profile add github:lem-project/lem#lem-webview
$ nix profile add github:lem-project/lem#lem-sdl2

Or run Lem temporarily (no install):

$ nix run github:lem-project/lem#
$ nix run github:lem-project/lem#lem-ncurses
$ nix run github:lem-project/lem#lem-webview
$ nix run github:lem-project/lem#lem-sdl2

Use the overlay when you already have a flake-based NixOS/home-manager config and want pkgs.lem-ncurses (and apps.lem-ncurses) available from your nixpkgs set. You can also consume lem as an overlay in flake.nix:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
    lem.url = "github:lem-project/lem";
  };

  outputs = { self, nixpkgs, lem, ... }: {
    nixosConfigurations.example = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [
        { nixpkgs.overlays = [ lem.overlays.default ]; }
        { environment.systemPackages = [ pkgs.lem-ncurses ]; }
      ];
    };
  };
}

docker

With Docker (terminal version):

$ docker run --rm -it ghcr.io/lem-project/lem:latest

Build

Instructions to build Lem on GNU/Linux, Macos and Windows.

Vision

Lem brings the distance between code and its execution state as close to zero as possible.
Users can see the results of their program while editing, without breaking their flow, and visually follow the behavior of the running code in real time.

The interface is consistently simple and easy to use without confusion.
Moreover, Lem is fully customizable, and any extensions take effect immediately as they are written.

Goals

Instantly reflect executed code inline
Visualize running code in real time
Provide a consistent UI that feels effortless to use
Maintain documentation for beginners, extension developers, and core developers.
Offer an intuitive and consistent API for extensions
Deliver a comfortable environment right out of the box