mkElmDerivation

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#+title: mkElmDerivation [[https://img.shields.io/badge/built%20with-Haskell-8f4e8b.svg]] [[https://img.shields.io/badge/built%20for-Elm-60b6cd.svg]] [[https://img.shields.io/github/license/jeslie0/mkelmderivation.svg]] [[https://img.shields.io/github/actions/workflow/status/jeslie0/mkElmDerivation/CI.yml.svg]]

This repository provides an unopinionated, general approach to packaging Elm projects. An overlay is provided, giving a function =mkElmDerivation= which is an overloaded version of nixpkgs's =mkDerivation=, but with all of your elm dependencies downloaded and stored in the right place. This allows you to package normal Elm projects, but also things like elm-spa and elm-watch apps. All of this is done by using your project's =elm.json= file, and requires no updating of nix files when you update your dependencies.

• Examples The following is the content of a =flake.nix= file, which can be used to build a normal elm project. #+begin_src nix { description = "An example flake for building elm projects.";

  inputs = { nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable"; mkElmDerivation.url = "github:jeslie0/mkElmDerivation"; };

  outputs = { self, nixpkgs, mkElmDerivation }: let system = "x86_64-linux";

  pkgs = import nixpkgs {
    overlays = [ mkElmDerivation.overlay ];
    inherit system;
  };
  in
    {
      packages = {
        default = pkgs.mkElmDerivation {
          name = "elm-example";
          src = ./.;
          elmJson = ./elm.json; # This defaults to ${src}/elm.json
          nativeBuildInputs =
            [ pkgs.elmPackages.elm ];
          buildPhase =
            ''
            elm make src/Main.elm --output Main.js --optimize
            '';
          installPhase =
            ''
            mkdir $out
            cp Main.js $out
            '';
        };
      };
    };
  

} #+end_src

We aren't restricted to just using Elm, however. Since this is just wrapper around =mkDerivation=, you can use whatever build inputs and build commands you want. See the [[./tests][tests]] directory for some more examples.

• Versions This project currently supports version 0.19.1 of Elm.

• Deprecations This project currently provides the functions =mkElmSpaDerivation= and =mkElmWatchDerivation=. The existence of these functions made sense when =mkElmDerivation= was more opinionated and less customizable; however, now that =mkElmDerivation= is more generic they aren't as useful. They will be kept in this project until the next major release, but I recommend not using them and instead using =mkElmDerivation= with a custom ~buildPhase~ and ~installPhase~.

• Updates Currently, a GitHub action is set to run at 0000 every Sunday. This will update the three JSON files stored in the [[file:mkElmDerivation/][mkElmDerivation directory]].