Add cython3 (python 3), move cython (python 2) to subfolder

pkgs/development/interpreters/cython/2/default.nix

@@ -15,7 +15,7 @@ stdenv.mkDerivation {
   buildInputs = [ python pkgconfig ];
 
   meta = {
-    description = "An interpreter to help writing C extensions for Python";
+    description = "An interpreter to help writing C extensions for Python 2";
     platforms = stdenv.lib.platforms.all;
   };
 }

pkgs/development/interpreters/cython/3/default.nix

@@ -0,0 +1,21 @@
+{ stdenv, fetchurl, python3, pkgconfig }:
+
+stdenv.mkDerivation {
+  name = "cython3-0.20";
+
+  src = fetchurl {
+    url = http://www.cython.org/release/Cython-0.20.tar.gz;
+    sha256 = "1a3m7zhw8mdyr95fwx7n1scrz82drr433i99dzm1n9dxi0cx2qah";
+  };
+
+  buildPhase = "python3 setup.py build --build-base $out";
+
+  installPhase = "python3 setup.py install --prefix=$out";
+
+  buildInputs = [ python3 pkgconfig ];
+
+  meta = {
+    description = "An interpreter to help writing C extensions for Python3";
+    platforms = stdenv.lib.platforms.all;
+  };
+}

pkgs/top-level/all-packages.nix

@@ -2345,7 +2345,8 @@ let
 
   cmucl_binary = callPackage ../development/compilers/cmucl/binary.nix { };
 
-  cython = callPackage ../development/interpreters/cython { };
+  cython = callPackage ../development/interpreters/cython/2 { };
+  cython3 = callPackage ../development/interpreters/cython/3 { };
 
   dylan = callPackage ../development/compilers/gwydion-dylan {
     dylan = callPackage ../development/compilers/gwydion-dylan/binary.nix {  };