nixpkgs.nix

(import <nixpkgs> {}).fetchFromGitHub {
  owner = "NixOS";
  repo = "nixpkgs";
  rev = "1233c8d9e9bc463899ed6a8cf0232e6bf36475ee";
  sha256 = "1lagfycy2lvfc8cdxk98dz2rxjlrbmv9hj42x0x40sy66bck1w0y";
}

pkgconfig.nix

{ compiler }:
{ packageOverrides = pkgs: {
    haskell = pkgs.haskell // {
      packages = pkgs.haskell.packages // {
        "${compiler}" = pkgs.haskell.packages."${compiler}".override {
          overrides = hpNew: hpOld: {
            classy-prelude-yesod =
              pkgs.haskell.lib.dontHaddock hpOld.classy-prelude-yesod;
            yesod-auth-simple =
              hpNew.callPackage ./yesod-auth-simple.nix {};
            wai-extra =
              hpNew.callPackage ./wai-extra.nix {};
            yesod-form =
              hpNew.callPackage ./yesod-form.nix {};
            yesod-core =
              hpNew.callPackage ./yesod-core.nix {};
            yesod-test =
              hpNew.callPackage ./yesod-test.nix {};
            ghc-exactprint =
              pkgs.haskell.lib.dontCheck hpOld.ghc-exactprint;
            yesod-paginator =
              hpNew.callPackage ./yesod-paginator.nix {};
          };
        };
      };
    };
  };
}

riskbook.nix

{ mkDerivation, aeson, amazonka, amazonka-core, amazonka-s3, base
, base64-bytestring, blaze-html, bytestring, case-insensitive
, classy-prelude, classy-prelude-conduit, classy-prelude-yesod
, conduit, conduit-extra, containers, data-default, directory
, errors, esqueleto, fast-logger, file-embed, foreign-store
, formatting, hedis, hjsmin, hspec, hspec-discover, http-api-data
, http-client, http-client-tls, http-conduit, http-types
, language-javascript, lens, lens-aeson, mime-mail, mime-mail-ses
, monad-control, monad-logger, mtl, network, network-uri
, persistent, persistent-postgresql, persistent-template
, postgresql-simple, postgresql-simple-migration, pretty-simple
, random, resourcet, rollbar, safe, safe-money, serialise
, shakespeare, split, stdenv, stm, template-haskell, text, th-nowq
, time, transformers, unordered-containers, uri-encode, utf8-string
, uuid, vector, wai, wai-extra, wai-logger, warp, websockets, wreq
, xmlbf, yaml, yesod, yesod-auth, yesod-auth-simple, yesod-core
, yesod-form, yesod-paginator, yesod-static, yesod-test
, yesod-websockets
}:
mkDerivation {
  pname = "riskbook";
  version = "0.0.0";
  src = ./.;
  isLibrary = true;
  isExecutable = true;
  enableSeparateDataOutput = true;
  libraryHaskellDepends = [
    aeson amazonka amazonka-core amazonka-s3 base base64-bytestring
    blaze-html bytestring case-insensitive classy-prelude
    classy-prelude-conduit classy-prelude-yesod conduit conduit-extra
    containers data-default directory errors esqueleto fast-logger
    file-embed foreign-store formatting hedis hjsmin http-api-data
    http-client http-client-tls http-conduit http-types
    language-javascript lens lens-aeson mime-mail mime-mail-ses
    monad-control monad-logger mtl network network-uri persistent
    persistent-postgresql persistent-template postgresql-simple
    postgresql-simple-migration random resourcet rollbar safe
    safe-money serialise shakespeare split stm template-haskell text
    th-nowq time transformers unordered-containers uri-encode
    utf8-string uuid vector wai wai-extra wai-logger warp websockets
    wreq xmlbf yaml yesod yesod-auth yesod-auth-simple yesod-core
    yesod-form yesod-paginator yesod-static yesod-websockets
  ];
  executableHaskellDepends = [
    aeson base bytestring case-insensitive classy-prelude
    classy-prelude-conduit classy-prelude-yesod conduit containers
    data-default directory esqueleto fast-logger file-embed
    foreign-store hjsmin http-conduit monad-control monad-logger
    persistent persistent-postgresql persistent-template pretty-simple
    safe shakespeare template-haskell text time unordered-containers
    vector wai wai-extra wai-logger warp yaml yesod yesod-auth
    yesod-core yesod-form yesod-paginator yesod-static
  ];
  testHaskellDepends = [
    aeson amazonka amazonka-s3 base bytestring case-insensitive
    classy-prelude classy-prelude-conduit classy-prelude-yesod conduit
    conduit-extra containers data-default directory esqueleto
    fast-logger file-embed foreign-store hjsmin hspec http-conduit
    http-types monad-control monad-logger persistent
    persistent-postgresql persistent-template resourcet safe safe-money
    shakespeare stm template-haskell text time unordered-containers
    uuid vector wai wai-extra wai-logger warp yaml yesod yesod-auth
    yesod-auth-simple yesod-core yesod-form yesod-paginator
    yesod-static yesod-test
  ];
  testToolDepends = [ hspec-discover ];
  license = stdenv.lib.licenses.gpl3;
}

shell.nix

let
  compiler = "ghc843";
  config = import ./pkgconfig.nix { inherit compiler; };
  pkgs = import (import ./nixpkgs.nix) { inherit config; };
  hpkgs = pkgs.haskell.packages.${compiler};
  pkg = hpkgs.callPackage (import ./riskbook.nix) {};

in
  {}: pkgs.lib.overrideDerivation pkg.env (old: {
        buildInputs = old.buildInputs ++ [
          hpkgs.hlint
          hpkgs.apply-refact
          pkgs.postgresql
          pkgs.redis
        ];

        shellHook = ''
          export PGDATA=~/tmp/pgdata;
        '';
      })