anchor.diff:    # Specify binaries to build in the form { foo.src = "src/foo.cr"; }
     # The default `crystal build` options can be overridden with { foo.options = [ "--optionname" ]; }
   , crystalBinaries ? { }
  +, enableParallelBuilding ? true
   , ...
   }@args:
   
  
positive.code: 
    buildDirectly = shardsFile == null || crystalBinaries != { };
  
  in
  stdenv.mkDerivation (mkDerivationArgs // {
  
  
negative.code:     "runHook preBuild"
    ] ++ lib.optional (format == "make")
      "make \${buildTargets:-build} $makeFlags"
    ++ lib.optionals (format == "crystal") (lib.mapAttrsToList mkCrystalBuildArgs crystalBinaries)
    ++ lib.optional (format == "shards")
      "shards build --local --production ${lib.concatStringsSep " " (args.options or defaultOptions)}"
    ++ [ "runHook postBuild" ]));
  