nixos haskell yesod package with overrides

create a new file my-stack-project.nix:

let
  pkgs = import  {};
  pkg = pkgs.haskellPackages.callCabal2nix "my-stack-project" ./. {};
in
  pkgs.haskell.lib.overrideCabal pkg (_: {
    doHaddock = false;
    postInstall = ''
      cp -r ./static $out/bin
      cp -r ./config $out/bin
    '';
  })