anchor.diff:  
         cryptohash-md5    = nixpkgs.haskell.lib.doJailbreak super.cryptohash-md5;
         cryptohash-sha1   = nixpkgs.haskell.lib.doJailbreak super.cryptohash-sha1;
  -      basement          = self.callCabal2nix "basement" (foundation-src + "/basement") {};
  -      foundation        = nixpkgs.haskell.lib.appendPatch super.foundation (nixpkgs.fetchpatch {
  -        url = "https://gitlab.haskell.org/ghc/head.hackage/-/raw/a89f0189a628e5de9a6e8fe9830e29a3e61e316c/patches/foundation-0.0.25.patch";
  -        sha256 = "0fhdqw01qqmzjn67d289m8gpb8wl1rwwc3hcjx92djxk493ialvj";
  -      });
  +      basement          = super.basement_0_0_12;
  +      foundation        = super.foundation_0_0_26_1;
         memory            = nixpkgs.haskell.lib.appendPatch super.memory (nixpkgs.fetchpatch {
           url = "https://gitlab.haskell.org/ghc/head.hackage/-/raw/c89c1e27af8f180b3be476e102147557f922b224/patches/memory-0.15.0.patch";
           sha256 = "0mkjbrzi05h1xds8rf5wfky176hrl03q0d7ipklp9x4ls3yyqj5x";
  
positive.code:   ghc-parser-src       = filterSource cleanSource ./ghc-parser;
    ihaskell-display-src = filterSource cleanSource ./ihaskell-display;
  
    foundation-src = nixpkgs.fetchFromGitHub {
      owner = "haskell-foundation";
      repo = "foundation";
      rev = "c87c00c5988398f7fb6bbf8ebc79250fc3e9a363";
      sha256 = "122kddjxyykkvw58v6wvvmgyqng9383iy2awpa39hs6zw0cbh3bl";
    };
    profunctors-src = nixpkgs.fetchFromGitHub {
      owner = "ekmett";
      repo = "profunctors";
  
negative.code: let
    nixpkgs-src = builtins.fetchTarball {
      url = "https://github.com/NixOS/nixpkgs/tarball/8795d39ce70f04e3fd609422d522e5b2594f3a70";
      sha256 = "01w7q0nqydippj0ygbg77byb770snhc5rnqzc6isws58642l8z4s";
    };
  in
  { compiler ? "ghc901"
  