Add two shell.nix to enable easier development on nixos.

shell-static.nix

@@ -0,0 +1,34 @@
+# This is a workaround meant for use with the nix package manager. If you don't know what it is or don't use it, please ignore this file.
+# 
+# The nk20 javascript static location are hardcoded for imperative system.
+# This make ./manage.py collectstatic hard to use with nixos.
+# 
+# A workaround is to enter a FHSUserEnv with the static placed under /share/javascript/<static>.
+# This emulate a debian like system and enable collecting static normally with ./manage.py collectstatics.
+# The regular shell.nix should be enough for other configurations.
+#
+# Warning, you are still supposed to use pip package with a venv !
+{ pkgs ? import <nixpkgs> {} }:
+(pkgs.buildFHSUserEnv {
+  name = "pipzone";
+  targetPkgs = pkgs: (with pkgs;
+  let
+    fhs-static = stdenv.mkDerivation {
+      name = "fhs-static";
+      buildCommand = ''
+      mkdir -p $out/share/javascript/bootstrap4
+      mkdir -p $out/share/javascript/jquery
+      ln -s ${python39Packages.xstatic-bootstrap}/lib/python3.9/site-packages/xstatic/pkg/bootstrap/data/* $out/share/javascript/bootstrap4
+      ln -s ${python39Packages.xstatic-jquery}/lib/python3.9/site-packages/xstatic/pkg/jquery/data/* $out/share/javascript/jquery
+    '';
+    };
+  in [
+    fhs-static
+    python39
+    gettext
+    python39Packages.pip
+    python39Packages.virtualenv
+    python39Packages.setuptools
+  ]);
+  runScript = "bash";
+}).env