Add nix config

nix-conf/home/includes/common.nix

@@ -63,6 +63,13 @@ in
     w3m
   ];
 
+  nix = {
+    package = pkgs.nix;
+    settings = {
+      extra-experimental-features = [ "nix-command" "flakes" ];
+    };
+  };
+
   programs.gpg.enable = true;
   programs.nix-index = {
     enable = true;

nix-conf/home/includes/darwin.nix

@@ -31,6 +31,12 @@
     wget
   ];
 
+  nix.settings = {
+    sandbox = true;
+    keep-outputs = true;
+    keep-derivations = true;
+  };
+
   programs.java = {
     enable = true;
     #package = (pkgs.jdk8.overrideAttrs (_: { postPatch = "ln -nsf ../zulu-8.jdk/Contents/Home/man man"; }));