anchor.diff:    scalacheck_flat = listToAttrs (flatten (mapAttrsToList (scalaVer: ss:
       mapAttrsToList (v: s: nameValuePair "scalacheck_${scalaVer}-${v}" s) ss
     ) scalacheck));
  +
  +  current = scalacheck."2.10.3"."1.10.1";
  +  snapshot = scalacheck."2.10.3"."1.11.0-SNAPSHOT";
   }
  
positive.code:       name = scalacheckVer;
        value = mkScalaCheck {
          name = "scalacheck_${scalaVer}-${scalacheckVer}";
          runTests = if scalacheck ? runTests then scalacheck.runTests else true;
          inherit scala;
          inherit (scalacheck) rev sha256;
  
negative.code: 
    mkScalaCheck = args: stdenv.mkDerivation rec {
      inherit (args) name;
      outputs = [ "jar" "srcjar" "doc" "docjar" ];
      src = fetchgit {
        url = scalacheckRepoUrl;
        inherit (args) rev sha256;
      };
      buildInputs = [ openjdk args.scala ];
      buildPhase = ''
        export LANG="en_US.UTF-8"
        export LOCALE_ARCHIVE=${glibcLocales}/lib/locale/locale-archive
  
        testinterface="${test-interface."1.0"}/lib/test-interface.jar"
  
        find src/main/scala -name '*.scala' > sources
  
        scalac \
          -classpath "$testinterface" \
          -optimise \
          -deprecation \
          -d ${name}.jar \
          @sources
  
        ${lib.optionalString args.runTests ''
          find src/test/scala -name '*.scala' > sources-test
          scalac \
            -classpath ${name}.jar \
            -optimise \
            -d ${name}-test.jar \
            @sources-test
          scala \
            -classpath ${name}.jar:${name}-test.jar \
            org.scalacheck.TestAll
        ''}
  
        jar cf "${name}-sources.jar" LICENSE RELEASE -C src/main/scala .
  
        mkdir api && scaladoc \
          -doc-title ScalaCheck \
          -doc-version "${args.version}" \
          -doc-footer "${docFooter args.version args.rev}" \
          -doc-source-url "${docSourceUrl args.version args.rev}" \
          -classpath "$testinterface" \
          -sourcepath src/main/scala \
          -d api \
          @sources
  
        jar cf "${name}-javadoc.jar" -C api .
      '';
      installPhase = ''
        mkdir -p "$jar" "$srcjar" "$doc" "$docjar"
        mv "${name}.jar" "$jar/"
        mv "${name}-sources.jar" "$srcjar/"
        mv "${name}-javadoc.jar" "$docjar/"
        mv api "$doc/"
      '';
    };
  
  