selfsym.nix

let
  overlay = self: super: {
    haskellPackages = with self.haskell.lib;
    super.haskell.packages.ghc865.override (old: {
      overrides = self.lib.composeExtensions (old.overrides or (_: _: { })) (hself: hsuper: {
        cabal2nix = super.haskellPackages.cabal2nix;
        hpack = dontCheck (hself.callHackage "hpack" "0.31.2" {});
        stack2cabal = hself.stack2cabal; #redundant right now
      });
    });
  };
  pkgs = import <nixpkgs> { overlays = [overlay]; config = {}; };
in
  pkgs.haskellPackages