Gleam 1.0 Release Overlay

I’ve only been using NixOS for a couple of weeks, so I didn’t feel qualified putting this in Guides, but I felt I should post something to help out.

The Gleam programming language recently released Version 1.0.0, which got it some coverage from the usual suspects on YouTube. I was intrigued and wanted to try it out, only to discover that nixpkgs (for the current release anyway) is still using version 0.32.4! Undeterred, I learned how to use overlays to build Gleam 1.0.0 myself and include it in a Nix shell.

As I said, I’m pretty new to Nix in general, so if you have advice on a better way to write any of this, I’m all ears.

Here’s the overlay:

final: prev: {
  gleam = prev.gleam.overrideAttrs (oldAttrs: rec {
    src = prev.fetchFromGitHub {
      owner = "gleam-lang";
      repo = "gleam";
      rev = "refs/tags/v1.0.0";
      hash = "sha256-gPlRihwK+J7s1SeymfVdVo/KIV+eEqxlLVOgsDWW9yo=";

    cargoDeps = oldAttrs.cargoDeps.overrideAttrs (prev.lib.const {
      name = "gleam-vendor.tar.gz";
      inherit src;
      outputHash = "sha256-JE8XRbAn7Y4szud3m68K2GT9wz/4YBpwD5UhU7f1Wio=";

and here’s a basic shell.nix that uses the overlay, assuming they are in the same directory:

{ pkgs ? import <nixpkgs> { overlays = [(import ./gleam-overlay.nix)]; } }:

pkgs.mkShell {
  buildInputs = with pkgs; [

Running gleam --version inside the shell should show 1.0.0.


Gleam has been bumped to 1.0.0 in the nixpkgs repo in the time since I wrote this post, see this PR. That was fast! You can access it via the unstable channel right now or you can keep using this overlay until it hits the stable channel.