default.nix

with import <nixpkgs> {};

haskellPackages.extend (self: super: {
  ray-tracer = self.callPackage ./ray-tracer.nix {};
  thing = self.callHackage "thing" "1.2.3" {};
})

ray-tracer.nix

{ mkDerivation, base, Chart, hip, hpack, lens, linear, stdenv }:
mkDerivation {
  pname = "ray-tracer";
  version = "0.1.0.0";
  src = ./.;
  isLibrary = true;
  isExecutable = true;
  libraryHaskellDepends = [ base Chart hip lens linear ];
  libraryToolDepends = [ hpack ];
  executableHaskellDepends = [ base hip lens linear ];
  testHaskellDepends = [ base hip lens linear ];
  preConfigure = "hpack";
  homepage = "https://github.com/githubuser/ray-tracer#readme";
  license = stdenv.lib.licenses.bsd3;
}