diff --git a/flake.nix b/flake.nix
index bb53bf5a..fc7b7ef5 100644
--- a/flake.nix
+++ b/flake.nix
@@ -316,6 +316,7 @@
 
         mkJupyterlab = {
           jupyterlabEnvArgs ? {},
+          notebookConfig ? {},
           kernels ? k: [], # k: [ (k.python {}) k.bash ],
           # extensions ? e: [], # e: [ e.jupy-ext ]
           runtimePackages ? [], # runtime package available to all binaries
@@ -390,14 +391,19 @@
           jupyterlabEnv = jupyterlabEnvWrapped (baseArgs // jupyterlabEnvArgs);
 
           # create directories for storing jupyter configs
-          jupyterDir = pkgs.runCommand "jupyter-dir" {} ''
-            # make jupyter config and data directories
-            mkdir -p $out/config $out/data
-            echo "c.NotebookApp.use_redirect_file = False" > $out/config/jupyter_notebook_config.py
-
-            # make jupyter lab user settings and workspaces directories
-            mkdir -p $out/config/lab/{user-settings,workspaces}
-          '';
+          jupyterDir = let
+            mergeNotebookConfig = lib.recursiveUpdate notebookConfig {
+              NotebookApp.use_redirect_file = false;
+              KernelSpecManager.whitelist = map (x: x.name) userKernels;
+            };
+          in
+            pkgs.runCommand "jupyter-dir" {} ''
+              # make jupyter config and data directories
+              mkdir -p $out/config $out/data
+              echo '${builtins.toJSON mergeNotebookConfig}' > $out/config/jupyter_notebook_config.json
+              # make jupyter lab user settings and workspaces directories
+              mkdir -p $out/config/lab/{user-settings,workspaces}
+            '';
 
           /*
           Finds kernels from kernelDerivations that have the same kernel
@@ -571,6 +577,7 @@
             mkJupyterlab
             mkJupyterlabFromPath
             mkJupyterlabNew
+            mkJupyterlabEval
             ;
         };
         packages =
@@ -624,7 +631,7 @@
         };
       }
     ))
-    // rec {
+    // {
       jupyterKernels = builtins.mapAttrs mkKernelFlakeOutput kernelsConfig.available;
       templates.default = {
         path = ./template;
diff --git a/modules/conf/jupyter_notebook_config.json b/modules/conf/jupyter_notebook_config.json
new file mode 100644
index 00000000..c1243385
--- /dev/null
+++ b/modules/conf/jupyter_notebook_config.json
@@ -0,0 +1,13 @@
+{
+  "LanguageServerManager": {
+    "language_servers": {
+      "haskell-language-server": {
+        "version": 2,
+        "argv": ["haskell-language-server-wrapper", "lsp"],
+        "languages": ["haskell"],
+        "display_name": "haskell-language-server",
+        "mimetypes": ["text/haskell", "text/x-haskell"]
+      }
+    }
+  }
+}
diff --git a/modules/default.nix b/modules/default.nix
index a6acc528..3810f8b9 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -19,6 +19,69 @@ in {
         description = "A list of runtime packages available to all binaries";
         default = [];
       };
+      notebookConfig = lib.mkOption {
+        type = types.attrs;
+        description = "jupyter notebook config which will be written to jupyter_notebook_config.py";
+        default = {};
+        apply = c: lib.recursiveUpdate (lib.importJSON ./conf/jupyter_notebook_config.json) c;
+      };
+
+      extensions = {
+        features = lib.mkOption {
+          type = types.listOf types.str;
+          description = "A list of features to enable";
+          default = [];
+          example = ["lsp"];
+        };
+        languageServers = lib.mkOption {
+          default = {};
+          description = "Which language servers package to use";
+          type = types.submodule {
+            options = {
+              python = lib.mkOption {
+                type = types.functionTo types.package;
+                description = "Python language server";
+                default = ps: ps.python-lsp-server;
+                example = lib.literalExpression ''
+                  if you want to use pyls-mypy or othter dependencies, you can do:
+                  extraPackages = ps: [] ++ python-lsp-server.passthru.optional-dependencies.all;
+                '';
+              };
+              haskell = lib.mkOption {
+                type = types.package;
+                description = "Haskell language server";
+                default = config.nixpkgs.haskell-language-server;
+                example = lib.literalExpression ''
+                  config.nixpkgs.haskell-language-server.override { supportedGhcVersions = [ "90" "94" ]; };
+                '';
+              };
+            };
+          };
+        };
+      };
+
+      jupyterlabEnvArgs = lib.mkOption {
+        type = types.submodule {
+          options =
+            {
+              extraPackages = lib.mkOption {
+                type = types.functionTo (types.listOf types.package);
+                default = ps: [];
+                example = ps: [ps.jupytext];
+                description = lib.mdDoc "A list of packages for extending the jupyterlab environment";
+              };
+            }
+            // (lib.recursiveUpdate (import ./types/poetry.nix {
+                inherit lib self;
+                config = config.jupyterlab.jupyterlabEnvArgs;
+              })
+              {
+                projectDir.default = self.outPath;
+              });
+        };
+        default = {};
+        description = "Arguments for the jupyterlab poetry's environment";
+      };
     };
 
     # flakes ? [], # flakes where to detect custom kernels/extensions
@@ -53,27 +116,73 @@ in {
   #++ map (name: ./. + "/../kernels/available/${name}/module.nix") (builtins.attrNames (builtins.readDir ./../kernels/available));
 
   config = {
-    build = mkJupyterlab {
-      #jupyterlabEnvArgs = config.jupyterlabEnvArgs;
-      kernels = availableKernels:
-        lib.flatten
-        (
-          builtins.map
+    build = let
+      findFeature = name:
+        if config.jupyterlab.extensions.features != []
+        then
           (
-            kernelTypeName:
-              builtins.map
-              (
-                kernelName:
-                  availableKernels.${kernelTypeName}
-                  config.kernel.${kernelTypeName}.${kernelName}.kernelArgs
-              )
-              (builtins.attrNames config.kernel.${kernelTypeName})
+            if (lib.intersectLists [name] config.jupyterlab.extensions.features) != []
+            then true
+            else false
           )
-          (builtins.attrNames config.kernel)
-        );
-      runtimePackages = config.jupyterlab.runtimePackages;
-      #flakes = config.flakes;
-    };
+        else false;
+
+      enabledLanguage = lang: feature:
+        (
+          if config.kernel.${lang} != {}
+          then true
+          else false
+        )
+        && (findFeature feature);
+    in
+      mkJupyterlab {
+        jupyterlabEnvArgs = {
+          inherit
+            (config.jupyterlab.jupyterlabEnvArgs)
+            pyproject
+            projectDir
+            editablePackageSources
+            preferWheels
+            poetrylock
+            poetry2nix
+            ;
+
+          # all of python packages should be kept in extraPackages, instead of runtimePackages
+          extraPackages = ps:
+            (lib.optionals (enabledLanguage "python" "lsp") [
+              (config.jupyterlab.extensions.languageServers.python ps)
+            ])
+            ++ (lib.optionals (findFeature "jupytext") [ps.jupytext])
+            ++ (lib.optionals (findFeature "lsp") [ps.jupyter-lsp])
+            ++ (config.jupyterlab.jupyterlabEnvArgs.extraPackages ps);
+        };
+
+        notebookConfig = config.jupyterlab.notebookConfig;
+
+        runtimePackages =
+          config.jupyterlab.runtimePackages
+          ++ (lib.optionals (enabledLanguage "haskell" "lsp") [
+            config.jupyterlab.extensions.languageServers.haskell
+          ]);
+
+        kernels = availableKernels:
+          lib.flatten
+          (
+            builtins.map
+            (
+              kernelTypeName:
+                builtins.map
+                (
+                  kernelName:
+                    availableKernels.${kernelTypeName}
+                    config.kernel.${kernelTypeName}.${kernelName}.kernelArgs
+                )
+                (builtins.attrNames config.kernel.${kernelTypeName})
+            )
+            (builtins.attrNames config.kernel)
+          );
+        #flakes = config.flakes;
+      };
     _module.args.pkgs = config.nixpkgs;
   };
 }
diff --git a/template/lsp.nix b/template/lsp.nix
new file mode 100644
index 00000000..b5c581c0
--- /dev/null
+++ b/template/lsp.nix
@@ -0,0 +1,40 @@
+{
+  pkgs,
+  config,
+  ...
+}: {
+  jupyterlab = {
+    extensions = {
+      features = ["lsp" "jupytext"];
+      languageServers = {
+        python = ps: ps.python-lsp-server;
+      };
+    };
+    notebookConfig = {
+      # add your custom language server config here or other notebook config for the jupyterlab_notebook_config.json
+      # LanguageServerManager.language_servers.pyls.serverSettings = {
+      # pyls.plugins.pycodestyle.enabled = true;
+      # }
+      # LanguageServerManager.language_servers.custom-language-servers
+      #   "argv" = ["haskell-language-server" "--lsp"];
+      #   "languages" = ["haskell"];
+      #   "display_name" = "haskell-language-server";
+      #   "mimetypes" = ["text/haskell" "text/x-haskell"];
+      #   server_settings = {
+      #   "haskell.plugin.ghcide-completions.globalOn" = true;
+      #
+      #   };
+      # };
+    };
+    runtimePackages = [];
+    jupyterlabEnvArgs.extraPackages = ps: ([] ++ ps.python-lsp-server.passthru.optional-dependencies.all);
+  };
+  kernel.python.minimal = {
+    enable = true;
+  };
+  # FIXME: haskell-language-server is not yet support in jupyterlab-lsp
+  kernel.haskell.minimal = {
+    enable = true;
+    haskellCompiler = "ghc902";
+  };
+}