{
  pkgs ? import (fetchTarball {
    url = "https://github.com/NixOS/nixpkgs/archive/4fe8d07066f6ea82cda2b0c9ae7aee59b2d241b3.tar.gz";
    sha256 = "sha256:06jzngg5jm1f81sc4xfskvvgjy5bblz51xpl788mnps1wrkykfhp";
  }) {}
}:

let
  r_pkgs = with pkgs.rPackages; [
    # rmarkdown-related packages.
    knitr
    rmarkdown
    tidyverse
    viridis
    # Rstudio-related packages.
    # servr
  ];
in
pkgs.mkShell {
  buildInputs = [
    pkgs.pandoc
    (pkgs.rWrapper.override {
      packages = r_pkgs;
    })

    # Uncomment to add RStudio in your environment.
    # (pkgs.rstudioWrapper.override {
    #  packages = r_pkgs;
    # })
  ];
}