Add flake

Author: matthewbauer

.github/workflows/test.yml

@@ -0,0 +1,19 @@
+name: "Test"
+on:
+  pull_request:
+  push:
+jobs:
+  tests:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - uses: cachix/install-nix-action@v10
+    - run: nix build
+     - run: nix-build -E '(import ./. {}).defaultPackage.${builtins.currentSystem}'
+    #- run: nix flake check
+    # - run: nix-build -E '(import ./. {}).checks.${builtins.currentSystem}'

README.md

@@ -4,7 +4,7 @@
 [![MELPA Stable](https://stable.melpa.org/packages/nix-mode-badge.svg)](https://stable.melpa.org/#/nix-mode)
 [![Build Status](https://travis-ci.com/NixOS/nix-mode.svg?branch=master)](https://travis-ci.com/NixOS/nix-mode)
 
-An emacs major mode for editing nix expressions. There is also a
+An Emacs major mode for editing Nix expressions. There is also a
 manual available at nix-mode.org.
 
 ## Submodes

default.nix

@@ -1,19 +1,3 @@
-{ pkgs ? import <nixpkgs> {}}:
-let
-  inherit (pkgs) emacsWithPackages stdenvNoCC texinfo git;
-  emacs = emacsWithPackages (epkgs: with epkgs; [
-    org-plus-contrib
-    company
-    json-mode
-    mmm-mode
-  ]);
-in stdenvNoCC.mkDerivation {
-  name = "nix-mode";
+(import (fetchTarball https://github.com/edolstra/flake-compat/archive/master.tar.gz) {
   src = ./.;
-  nativeBuildInputs = [ emacs texinfo git ];
-  makeFlags = [ "PREFIX=$(out)" ];
-  shellHook = ''
-    echo Run make run to get vanilla emacs with nix-mode loaded.
-  '';
-  doCheck = true;
-}
+}).defaultNix

flake.lock

@@ -0,0 +1,38 @@
+{
+  description = "An emacs major mode for editing Nix expressions";
+
+  inputs.nixpkgs.url = "nixpkgs/nixos-20.03-small";
+
+  outputs = { self, nixpkgs }: let
+    systems = [ "x86_64-linux" "i686-linux" "x86_64-darwin" "aarch64-linux" ];
+    forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f system);
+  in {
+    packages = forAllSystems (system: with (import nixpkgs { inherit system; }); {
+      nix-mode = let
+        emacs = emacsWithPackages (epkgs: with epkgs; [
+          org-plus-contrib
+          company
+          json-mode
+          mmm-mode
+        ]);
+      in stdenvNoCC.mkDerivation {
+        name = "nix-mode";
+        src = self;
+        nativeBuildInputs = [ emacs texinfo git ];
+        makeFlags = [ "PREFIX=$(out)" ];
+        shellHook = ''
+          echo Run make run to get vanilla emacs with nix-mode loaded.
+        '';
+        doCheck = true;
+      };
+    });
+
+    defaultPackage = forAllSystems (system: self.packages.${system}.nix-mode);
+
+    # checks are run in ‘make check’ right now we should probably move
+    # these to its own derivation
+    checks = forAllSystems (system: {
+      inherit (self.packages.${system}) nix-mode;
+    });
+  };
+}