anchor.diff:  { stdenv, pkgsHostTarget, cmake, makeWrapper, mkDerivation, fetchFromGitHub
   , alex, array, base, bytestring, cond, containers, directory, extra
  -, filepath, haskeline, hpack, hspec, hspec-core, json, lib, mtl
  +, filepath, hpack, hspec, hspec-core, isocline, json, lib, mtl
   , parsec, process, regex-compat, text, time }:
   
   let
  -  version = "2.1.9";
  +  version = "2.3.1";
     src = fetchFromGitHub {
       owner = "koka-lang";
       repo = "koka";
       rev = "v${version}";
  -    sha256 = "0xny4x1a2lzwgmng60bni7rxfjx5ns70qbfp703qwms54clvj5wy";
  +    sha256 = "18f4hsqgc6c0cnayabj311n438fjhf217j1kjaysa8w4k4pxl58z";
       fetchSubmodules = true;
     };
     kklib = stdenv.mkDerivation {
  
positive.code:   isExecutable = true;
    libraryToolDepends = [ hpack ];
    executableHaskellDepends = [
      array base bytestring cond containers directory haskeline 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" \
  
negative.code:   prePatch = "hpack";
    description = "Koka language compiler and interpreter";
    homepage = "https://github.com/koka-lang/koka";
    changelog = "${homepage}/blob/master/doc/spec/news.mdk";
    license = lib.licenses.asl20;
    maintainers = with lib.maintainers; [ siraben sternenseemann ];
  }
  