add treefmt and jupyter lab

flake.nix

@@ -0,0 +1,58 @@
+{
+  description = "Your jupyenv project";
+
+  nixConfig.extra-substituters = [
+    "https://tweag-jupyter.cachix.org"
+  ];
+  nixConfig.extra-trusted-public-keys = [
+    "tweag-jupyter.cachix.org-1:UtNH4Zs6hVUFpFBTLaA4ejYavPo5EFFqgd7G7FxGW9g="
+  ];
+
+  inputs = {
+    treefmt-nix.url = "github:numtide/treefmt-nix";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    flake-parts.inputs.nixpkgs-lib.follows = "nixpkgs";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    jupyenv.url = "github:tweag/jupyenv";
+  };
+
+  outputs =
+    inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      imports = [ ./treefmt.nix ];
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+      ];
+      perSystem =
+        {
+          lib,
+          system,
+          pkgs,
+          ...
+        }:
+        let
+          inherit (inputs.jupyenv.lib.${system}) mkJupyterlabNew;
+          jupyterlab = mkJupyterlabNew (
+            { ... }:
+            {
+              # nixpkgs = nixpkgs;
+              imports = [ (import ./kernels.nix) ];
+            }
+          );
+        in
+        {
+          devShells.default = pkgs.mkShell {
+            buildInputs = with pkgs; [
+              tex-fmt
+            ];
+          };
+          packages = {
+            inherit jupyterlab;
+          };
+          packages.default = jupyterlab;
+          apps.default.program = "${jupyterlab}/bin/jupyter-lab";
+          apps.default.type = "app";
+        };
+    };
+}