Infrastructure update

.default.nix

@@ -1,8 +1,16 @@
-with import <nixpkgs> {}; {
-  autocmakeEnv = stdenv.mkDerivation {
+let
+  hostPkgs = import <nixpkgs> {};
+  nixpkgs = (hostPkgs.fetchFromGitHub {
+    owner = "NixOS";
+    repo = "nixpkgs-channels";
+    rev = "nixos-unstable";
+    sha256 = "15fcl29a97f68j1pjywmrjm31rdh1a21jz9airlsbzpl4lc3zhfi";
+  });
+in
+  with import nixpkgs {};
+  stdenv.mkDerivation {
     name = "Autocmake";
     buildInputs = [
-      atlas
       ccache
       clang
       cmake
@@ -10,10 +18,15 @@ with import <nixpkgs> {}; {
       gfortran
       liblapack
       openmpi
-      python35Packages.pep8
-      python35Packages.pytest
-      python35Packages.pyyaml
+      pipenv
+      python3Packages.pep8
+      python3Packages.pytest
+      python3Packages.pyyaml
       zlib
     ];
-  };
-}
+    src = null;
+    shellHook = ''
+    export NINJA_STATUS="[Built edge %f of %t in %e sec]"
+    SOURCE_DATE_EPOCH=$(date +%s)
+    '';
+  }