nixpkgs:

{  name  # the main module namespace
,  nick  # a short name, for the executable
,  deps  # deps get passed to ghc
}:

with nixpkgs;

let
  nsToPath = ns: builtins.toString (builtins.replaceStrings ["."] ["/"] ns);

  path = nsToPath name;

  depsToPackageSet = packageSet: deps:
    map (s: builtins.getAttr s packageSet) deps;

  claySrc = pkgs.fetchFromGitHub {
    owner = "sebastiaanvisser";
    repo = "clay";
    rev = "cc7729b1b42a79e261091ff7835f7fc2a7ae3cee";
    sha256 = "1vd67976lvi5l4qq18zy6j44apynkl44ps04p8vwfx4gzr895dyp";
  };

  ghc865_ = pkgs.haskell.packages.ghc865.override (oldAttrs: {
    overrides = with pkgs.haskell.lib; self: super: {
      clay = self.callCabal2nix "clay" claySrc {};
      wai-middleware-metrics = dontCheck super.wai-middleware-metrics;
    };
  });

  ghc = ghc865_.ghcWithPackages (hp: depsToPackageSet hp deps);

in stdenv.mkDerivation {
  name = name;
  version = "0";
  src = ../../.; # this is the git root
  nativeBuildInputs = [ ghc ];
  strictDeps = true;
  buildPhase = ''
    #
    mkdir -p $out/{bin,static} ${path}
    #
    # compile with ghc
    #
    ${ghc}/bin/ghc -Werror -i. \
        --make ${path}.hs \
        -main-is ${name} \
        -o $out/bin/${nick}
  '';
  # the install process was handled above
  installPhase = "exit 0";
} // { env = ghc; }