nixpkgs.nix

{ system ? builtins.currentSystem }:
let
  nixpkgs = builtins.fetchTarball {
    url = "https://github.com/NixOS/nixpkgs-channels/archive/nixos-19.03.tar.gz";
    sha256 = "06cqc37yj23g3jbwvlf9704bl5dg8vrzqvs5y2q18ayg9sw61i6z";
  };
in
  import nixpkgs {
    inherit system;
    config = {}; # prevent nixpkgs from loading user configuration
    overlays = [ (import ./overlay.nix) ];
  }

overlay.nix

self: super:

let haskellOverlay = hself: hsuper: {
  inline-r = self.haskell.lib.dontCheck (super.haskellPackages.inline-r);
};

in

{
  haskellPackages = super.haskellPackages.override { overrides = haskellOverlay; };
}

shell.nix

{ pkgs ? import ./nix/nixpkgs.nix {} }:

pkgs.haskellPackages.shellFor
{
  packages = ps: [ ps.inline-r ];
  withHoogle = false;
  buildInputs = [ ];
}