anchor.diff:    src = fetchFromGitHub {
       owner = "Ripser";
       repo = "ripser";
  -    rev = "f69c6af6ca6883dd518c48faf41cf8901c379598";
  -    sha256 = "1mw2898s7l29hgajsaf75bs9bjn2sn4g2mvmh41a602jpwp9r0rz";
  +    rev = "v${version}";
  +    sha256 = "sha256-BxmkPQ/nl5cF+xwQMTjXnLgkLgdmT/39y7Kzl2wDfpE=";
     };
  -
  -  #Patch from dev branch to make compilation work.
  -  #Will be removed when it gets merged into master.
  -  patches = [(fetchurl {
  -    url = "https://github.com/Ripser/ripser/commit/dc78d8ce73ee35f3828f0aad67a4e53620277ebf.patch";
  -    sha256 = "1y93aqpqz8fm1cxxrf90dhh67im3ndkr8dnxgbw5y96296n4r924";
  -  })];
   
     buildInputs = optional useGoogleHashmap sparsehash;
   
     buildFlags = [
       "-std=c++11"
  -    "-Ofast"
  +    "-O3"
       "-D NDEBUG"
     ]
  -  ++ optional assembleReductionMatrix "-D ASSEMBLE_REDUCTION_MATRIX"
     ++ optional useCoefficients "-D USE_COEFFICIENTS"
     ++ optional indicateProgress "-D INDICATE_PROGRESS"
     ++ optional useGoogleHashmap "-D USE_GOOGLE_HASHMAP"
  
positive.code: 
  let
    inherit (lib) optional;
    version = "1.0";
  in
  stdenv.mkDerivation {
    pname = "ripser";
  
negative.code: { lib, stdenv, fetchFromGitHub
  , useCoefficients ? false
  , indicateProgress ? false
  , useGoogleHashmap ? false, sparsehash ? null
  