anchor.diff:        url = "http://haskell.org/ghc/dist/${version}/ghc-${version}-x86_64-deb9-linux.tar.xz";
         sha256 = "1pqlx6rdjs2110g0y1i9f8x18lmdizibjqd15f5xahcz39hgaxdw";
       };
  +    aarch64-linux = {
  +      url = "http://haskell.org/ghc/dist/${version}/ghc-${version}-aarch64-ubuntu18.04-linux.tar.xz";
  +      sha256 = "11n7l2a36i5vxzzp85la2555q4m34l747g0pnmd81cp46y85hlhq";
  +    };
       x86_64-darwin = {
         url = "http://haskell.org/ghc/dist/${version}/ghc-${version}-x86_64-apple-darwin.tar.xz";
         sha256 = "0s9188vhhgf23q3rjarwhbr524z6h2qga5xaaa2pma03sfqvvhfz";
  
positive.code:     or (throw "cannot bootstrap GHC on this platform"));
  
    nativeBuildInputs = [ perl ];
  
    # Cannot patchelf beforehand due to relative RPATHs that anticipate
    # the final install location/
  
negative.code: { stdenv
  , fetchurl, perl, gcc
  , ncurses5, gmp, glibc, libiconv
  , llvmPackages
  }:
  
  # Prebuilt only does native
  assert stdenv.targetPlatform == stdenv.hostPlatform;
  
  let
    useLLVM = !stdenv.targetPlatform.isx86;
  
    libPath = stdenv.lib.makeLibraryPath ([
      ncurses5 gmp
    ] ++ stdenv.lib.optional (stdenv.hostPlatform.isDarwin) libiconv);
  