Useful template compiling a Haskell project with Nix

release.nix

{ compiler ? "ghc864" }:

let
  # Disable tests for these packages
  dontCheckPackages = [
  ];

  # Jailbreak these packages
  doJailbreakPackages = [
  ];

  # Disable haddocks for these packages
  dontHaddockPackages = [
  ];

  config = {
    packageOverrides = pkgs: rec {
      haskell = pkgs.haskell // {
        packages = pkgs.haskell.packages // {
          "${compiler}" =
            let
                generatedOverrides = haskellPackagesNew: haskellPackagesOld:
                  let
                    toPackage = file: _: {
                      name  = builtins.replaceStrings [ ".nix" ] [ "" ] file;

                      value = haskellPackagesNew.callPackage (./. + "/nix/${file}") { };
                    };

                  in
                    pkgs.lib.mapAttrs' toPackage (builtins.readDir ./nix);

                makeOverrides =
                  function: names: haskellPackagesNew: haskellPackagesOld:
                    let
                      toPackage = name: {
                        inherit name;

                        value = function haskellPackagesOld.${name};
                      };

                  in
                    builtins.listToAttrs (map toPackage names);

                composeExtensionsList =
                  pkgs.lib.fold pkgs.lib.composeExtensions (_: _: {});

                # More exotic overrides go here
                manualOverrides = haskellPackagesNew: haskellPackagesOld: {
                };
            in
              pkgs.haskell.packages."${compiler}".override {
                   overrides = composeExtensionsList [
                            generatedOverrides
                            (makeOverrides pkgs.haskell.lib.dontCheck   dontCheckPackages  )
                            (makeOverrides pkgs.haskell.lib.doJailbreak doJailbreakPackages)
                            (makeOverrides pkgs.haskell.lib.dontHaddock dontHaddockPackages)
                            manualOverrides
                          ];
              };
        };
      };
    };
  };

  pkgs = import <nixpkgs> { inherit config; };

in
  { project = pkgs.haskell.packages."${compiler}".project;
  }

This is a combination of https://github.com/Gabriel439/haskell-nix/blob/master/project1/release5.nix and https://github.com/Gabriel439/haskell-nix/blob/master/project4/release3.nix