scala: Init 2.13

Make 2.13 the default, move 2.12 from default.nix to 2.12.nix

pkgs/development/compilers/scala/2.13.nix

@@ -0,0 +1,46 @@
+{ stdenv, fetchurl, makeWrapper, jre, gnugrep, coreutils }:
+
+stdenv.mkDerivation rec {
+  name = "scala-2.13.0";
+
+  src = fetchurl {
+    url = "https://www.scala-lang.org/files/archive/${name}.tgz";
+    sha256 = "12g0a9i0xxqxxcvmimm5w2wgmrdhq80p8bsp52d6yldz4lrnbm7p";
+  };
+
+  propagatedBuildInputs = [ jre ] ;
+  buildInputs = [ makeWrapper ] ;
+
+  installPhase = ''
+    mkdir -p $out
+    rm "bin/"*.bat
+    mv * $out
+
+    # put docs in correct subdirectory
+    mkdir -p $out/share/doc
+    mv $out/doc $out/share/doc/scala
+
+    for p in $(ls $out/bin/) ; do
+      wrapProgram $out/bin/$p \
+        --prefix PATH ":" ${coreutils}/bin \
+        --prefix PATH ":" ${gnugrep}/bin \
+        --prefix PATH ":" ${jre}/bin \
+        --set JAVA_HOME ${jre}
+    done
+  '';
+
+  meta = {
+    description = "General purpose programming language";
+    longDescription = ''
+      Scala is a general purpose programming language designed to express
+      common programming patterns in a concise, elegant, and type-safe way.
+      It smoothly integrates features of object-oriented and functional
+      languages, enabling Java and other programmers to be more productive.
+      Code sizes are typically reduced by a factor of two to three when
+      compared to an equivalent Java application.
+    '';
+    homepage = https://www.scala-lang.org/;
+    license = stdenv.lib.licenses.bsd3;
+    platforms = stdenv.lib.platforms.all;
+  };
+}

pkgs/top-level/all-packages.nix

@@ -8044,8 +8044,9 @@ in
 
   scala_2_10 = callPackage ../development/compilers/scala/2.10.nix { };
   scala_2_11 = callPackage ../development/compilers/scala/2.11.nix { };
-  scala_2_12 = callPackage ../development/compilers/scala { jre = jre8; };
-  scala = scala_2_12;
+  scala_2_12 = callPackage ../development/compilers/scala/2.12.nix { jre = jre8; };
+  scala_2_13 = callPackage ../development/compilers/scala/2.13.nix { jre = jre8; };
+  scala = scala_2_13;
 
   scalafix = callPackage ../development/tools/scalafix { };
   scalafmt = callPackage ../development/tools/scalafmt { };