shell.nix

let
  myHaskellPackageOverlay = self: super: {
    haskellPackages = super.haskellPackages.override {
    overrides = hself: hsuper: {
        mkDerivation = args: hsuper.mkDerivation (args // {
          doCheck = false;
          doHaddock = false;
          jailbreak = true;
        });
        random =
          let newRandomSrc = builtins.fetchGit {
                url = "https://github.com/idontgetoutmuch/random.git";
                rev = "83262ccd8a2d4b8f29b14c535b6bdf997bc7a497";
                ref = "interface-to-performance";
              };
          in
          # Since cabal2nix has a transitive dependency on random, we need to
          # get the callCabal2nix function from the normal haskellPackages that
          # is not being overridden.
          (import <nixpkgs> {}).haskell.lib.dontCheck ((import <nixpkgs> {}).haskellPackages.callCabal2nix "random" newRandomSrc { });
      };
    };
  };

in

{ pkgs ? import <nixpkgs> { overlays = [ myHaskellPackageOverlay ]; }, doBenchmark ? false }:

let

  haskellDeps = ps: with ps; [
    random    # (pkgs.haskell.lib.dontCheck random)
    splitmix  # (pkgs.haskell.lib.doJailbreak splitmix)
  ];

in

  pkgs.stdenv.mkDerivation {
  name = "env";
  buildInputs = [
    (pkgs.haskellPackages.ghcWithPackages haskellDeps)
  ];
}