Add sagemath notebook flake

sagemath-notebook/flake.nix

@@ -0,0 +1,36 @@
+{
+  description = "Sagemath flake";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05";
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils}:
+    flake-utils.lib.eachDefaultSystem
+    (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfree = true;
+        };
+        python-packages = ps: with ps; [
+          jupyterlab
+          jupyterlab-git
+          jupyterlab-lsp
+          jupyterlab-widgets
+        ];
+      in {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            sage
+            (python311.withPackages python-packages)
+          ];
+
+          shellHook = ''
+            # sage --nodotsage -n --notebook-dir .
+            # TODO sage --nodotsage -n=jupyterlab --notebook-dir .
+            # exit
+          '';
+        };
+      }
+    );
+}