hakyll-nix-template

Hakyll + Nix template

Features

nix flakes

• Build your site into the ./result/dist folder:

  λ nix build
  

• Start hakyll's dev server that reloads when changes are made:

  λ nix run . watch
  Listening on http://127.0.0.1:8000
  ...more logs
  

• Run any hakyll command through nix run .!

  λ nix run . clean
  Removing dist...
  Removing ssg/_cache...
  Removing ssg/_tmp...
  

• Start a development environment that

  • has your shell environment
  • has hakyll-site (for building/watching/cleaning hakyll projects)
  • has hakyll-init (for generating new projects)
  • can have anything else you put in the buildInputs of the devShell in flake.nix; for example: haskell-language-server, hlint, and ormolu
  • is set up to run ghci with some defaults and the modules loaded so you can make your own changes and test them out in the ghci REPL

  λ nix develop
  
  [hakyll]λ hakyll-site build
  ...
  Success
  
  [hakyll]λ ghci
  ...
  [1 of 2] Compiling Slug    ( ssg/src/Slug.hs, interpreted )
  [2 of 2] Compiling Main    ( ssg/src/Main.hs, interpreted )
  ...
  
  λ > :type toSlug
  toSlug :: T.Text -> T.Text
  
  λ > import Data.Text (pack)
  λ > toSlug (pack "What If I Told You...")
  "what-if-i-told-you"
  

• Easily unbreak hakyll's nixpkgs distribution or change hakyll's compile flags via the ./haskell-overlay.nix and hakyll.patch files

hakyll

All of this is custmomizable, and here are some things that are already done for you:

• pandoc markdown customization to make it as close to GitHub's markdown style as possible
• Slug.hs module that makes nice link URIs based on post titles
• RSS & Atom XML feed generation
• Sitemap generation
• Code syntax highlighting customization
• ...other reasonable defaults

Configure the dev server, cache & tmp directories, and more in ./ssg/src/Main.hs.

Deployment

Deployment is set up through a GitHub Action with cachix, and it deploys to a GitHub Pages branch, gh-pages, when you merge code into your main branch.

Setup information can be found below in the "Cachix" section.

Note: If your main branch's name isn't main, ensure 'refs/heads/main' gets updated to 'refs/heads/my-main-branch' in ./github/workflows/main.yml.

Setup

Nix Flakes

If you don't have nix and are not running macOS, follow the nix installation instructions.

At the time of writing, the macOS installation is in a weird place. You should use this:

λ sh <(curl https://abathur-nix-install-tests.cachix.org/serve/yihf8zbs0jwph2rs9qfh80dnilijxdi2/install) --tarball-url-prefix https://abathur-nix-install-tests.cachix.org/serve

Once you have nix installed, follow the instructions here to get access to flakes: https://nixos.wiki/wiki/Flakes.

Cachix

The ./.github/workflows/main.yml file builds with help from cachix, so you'll to generate a signing key to be able to do this.

1. Create a cache on cachix for your project
2. Follow cachix's instructions to generate a signing keypair
3. Copy the signing keypair value to a new CACHIX_SIGNING_KEY secret on https://github.com/settings/secrets

Enable Content-Addressible Derivation (experimental)

Given you have your nix conf experimental-features set to something like

experimental-features = "nix-command flakes ca-derivations ca-references"

Uncomment the __contentAddressed = true; line in haskell-ovelray.nix, and then run

λ nix build --experimental-features "ca-derivations flakes nix-command"

Alternatives to the haskell overlay

Overriding legacyPackages' haskell compiler packages

pkgs = nixpkgs.legacyPackages.${system};
myHaskellPackages = pkgs.haskell.packages.${haskellCompiler}.override {
  overrides = hpFinal: hpPrev:
    let
      hakyll-src = hpPrev.callHackage "hakyll" "4.14.0.0" {};
      pandoc-src = hpPrev.callHackage "pandoc" "2.11.4" {};
    in {
      hakyll = pipe hakyll-src [
        doJailbreak
        dontCheck
        (withPatch ./hakyll.patch)
        (withFlags [ "-f" "watchServer" "-f" "previewServer" ])
      ];

      pandoc = pipe pandoc-src [
        doJailbreak
        dontCheck
      ];
    };
};

Pulling hakyll-src from GitHub

hakyll-src, used in the haskell-overlay.nix and in the prior example, doesn't have to come from hackage; it could come from what your pinned nixpkgs version has via hakyll-src = hpPrev.hakyll, or it could come from the hakyll repo pinned as a nix flake input:

hakyll-src = {
  url = "github:jaspervdj/hakyll/v4.14.0.0";
  flake = false;
};

...and then:

hakyll-src = hpPrev.callCabal2nix "hakyll" hakyll-src {};