anchor.diff:    isExecutable = true;
     libraryToolDepends = [ hpack ];
     executableHaskellDepends = [
  -    array base bytestring cond containers directory haskeline mtl
  +    array base bytestring cond containers directory isocline mtl
       parsec process text time kklib
     ];
     executableToolDepends = [ alex makeWrapper ];
     postInstall = ''
       mkdir -p $out/share/koka/v${version}
       cp -a lib $out/share/koka/v${version}
  -    cp -a contrib $out/share/koka/v${version}
       cp -a kklib $out/share/koka/v${version}
       wrapProgram "$out/bin/koka" \
         --set CC "${lib.getBin cc}/bin/${cc.targetPrefix}cc" \
  
positive.code:   prePatch = "hpack";
    description = "Koka language compiler and interpreter";
    homepage = "https://github.com/koka-lang/koka";
    license = lib.licenses.asl20;
    maintainers = with lib.maintainers; [ siraben sternenseemann ];
  }
  
negative.code: { stdenv, pkgsHostTarget, cmake, makeWrapper, mkDerivation, fetchFromGitHub
  , alex, array, base, bytestring, cond, containers, directory, extra
  , filepath, hpack, hspec, hspec-core, isocline, json, lib, mtl
  , parsec, process, regex-compat, text, time }:
  
  let
    version = "2.3.1";
    src = fetchFromGitHub {
      owner = "koka-lang";
      repo = "koka";
      rev = "v${version}";
      sha256 = "18f4hsqgc6c0cnayabj311n438fjhf217j1kjaysa8w4k4pxl58z";
      fetchSubmodules = true;
    };
    kklib = stdenv.mkDerivation {
  