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Emacs Dart IDE using lsp-mode to connect to Dart Analysis Server.

flutter_logo LSP works great with Flutter, but there are also other packages that may help to improve your development, for more info see Additional packages.


The following has a example to setup lsp-dart.

(require 'package)
(add-to-list 'package-archives '("melpa" . "") t)

(setq package-selected-packages 
  '(dart-mode lsp-mode lsp-dart lsp-treemacs flycheck company
    ;; Optional packages
    lsp-ui company hover))

(when (cl-find-if-not #'package-installed-p package-selected-packages)
  (mapc #'package-install package-selected-packages))

(add-hook 'dart-mode-hook 'lsp)

(setq gc-cons-threshold (* 100 1024 1024)
      read-process-output-max (* 1024 1024))


Besides the lsp-mode features, lsp-dart implements the custom methods features from the dart_analysis_server.

Closing labels#


Tree views#

lsp-dart uses lsp-treemacs for rendering some tree views features.

lsp-dart-show-outline ⚠*


lsp-dart-show-flutter-outline ⚠*


Run/Debug tests#

lsp-dart-run-all-tests - Run all tests from project.

lsp-dart-run-test-file - Run all tests from current test buffer.

lsp-dart-run-test-at-point - Run single test at point.

lsp-dart-debug-test-at-point - Debug single test at point.

lsp-dart-visit-last-test - Go to last ran test.

lsp-dart-run-last-test - Run last ran test.

lsp-dart-debug-last-test - Debug last ran test.

Running a test interactively:


Test tree#

lsp-dart-test-show-tree - Open the test tree containing the latest ran tests.


For more options, check the settings section.

Flutter colors#

Display the flutter colors on left fringe.


You can disable the feature setting lsp-dart-flutter-fringe-colors to nil.

Flutter widget guides#

Display widget guide lines from parent to child widgets on flutter. ⚠*


You can disable the feature setting lsp-dart-flutter-widget-guides to nil.

Run or Debug#

To run your app you can use lsp-dart-run which will use dap-mode but for running without debug. to pass custom arguments it's possible to pass a prefix-argument with arguments separated by space.

For debugging, lsp-dart uses dap-mode. You only need to run lsp-dart-dap-setup one time to setup the debugger to your Emacs and dap-debug to start the debug.



lsp-dart support Flutter debugging too via dap-debug with an option to select the device to debug.


After the debug session has started, you can run:

lsp-dart-flutter-hot-restart - Trigger Flutter hot restart on the debug sessions.

lsp-dart-flutter-hot-reload - Trigger Flutter hot reload on the debug sessions.

For hot-reload/restart on buffer save you can enable lsp-dart-dap-flutter-hot-reload-on-save or lsp-dart-dap-flutter-hot-restart-on-save.

Custom templates#

You can register a custom template for debugging with dap-register-debug-template, check the following example:

(use-package lsp-dart
  :ensure t
  :hook (dart-mode . lsp)
  (dap-register-debug-template "Flutter :: Custom debug"
                               (list :flutterPlatform "x86_64"
                                     :program "lib/main_debug.dart"
                                     :args '("--flavor" "customer_a"))))
flutterPlatform,:program, and :args are all optional.

A full list of supported parameters can be found in the source of the function lsp-dart-dap--populate-flutter-start-file-args in lsp-dart-dap.el. Several of these parameters can be configured by setting one of the Supported settings with matching names.


You can also open the Dart DevTools on the current debug session with lsp-dart-open-devtools.


lsp-dart supports running Flutter and Dart commands as following:

lsp-dart-pub-get - Run pub get or flutter pub get on project root.

lsp-dart-pub-upgrade - Run pub upgrade or flutter pub upgrade on project root.

lsp-dart-pub-outdated - Run pub outdated or flutter pub outdated on project root.

⚠* Features only available for Dart SDK version 2.8.0 or above.#

Supported settings#

Variable Description Default
lsp-dart-sdk-dir The optional Dart SDK path. If nil and in a flutter project, it will try to find the dart SDK from Flutter SDK cache dir, otherwise it will search for a dart executable in $PATH. nil
lsp-dart-flutter-sdk-dir The optional Flutter SDK path. If nil, it will try to find the Flutter SDK from the flutter executable in $PATH and if not found, it will try in $FLUTTER_ROOT. nil
lsp-dart-flutter-executable Flutter executable name. flutter
lsp-dart-server-command analysis_server executable to use Check source file
lsp-dart-project-root-discovery-strategies Strategies to find project root to run most lsp-dart commands '(lsp-root closest-pubspec)'
lsp-dart-enable-sdk-formatter Whether to enable server formatting. t
lsp-dart-line-length Line length used by server formatter. 80
lsp-dart-show-todos Whether to generate diagnostics for TODO comments. If unspecified, diagnostics will not be generated. nil
lsp-dart-complete-function-calls Completes functions/methods with their required parameters. t
lsp-dart-extra-library-directories Extra libs to analyze besides Dart SDK libs '()
lsp-dart-only-analyze-projects-with-open-files Analysis will only be performed for projects that have open files rather than the root workspace folder nil
lsp-dart-suggest-from-unimported-libraries Completion will not include symbols that are not already imported into the current file. t
lsp-dart-closing-labels Enable the closing labels feature on server lsp t
lsp-dart-closing-labels-prefix The prefix string to be concatenated with the closing label ""
lsp-dart-closing-labels-size The font size factor to be multiplied by the closing labels font size 0.9
lsp-dart-outline Enable the outline tree view feature on server lsp t
lsp-dart-outline-position-params The outline tree position params. Left side
lsp-dart-flutter-outline Whether to enable the Flutter outline tree view feature on server lsp t
lsp-dart-flutter-outline-position-params The Flutter outline tree position params Left side
lsp-dart-flutter-fringe-colors Enable the Flutter colors on fringe. t
lsp-dart-flutter-widget-guides Enable the Flutter widget guide lines from parent to child widgets t
lsp-dart-test-pop-to-buffer-on-run Whether to pop to tests buffer on run, only display or do nothing. display-only
lsp-dart-test-tree-on-run Whether to pop to tests tree buffer on run t
lsp-dart-test-tree-position-params The test tree position params Treemacs default
lsp-dart-test-tree-line-spacing The test tree line spacing between nodes 4
lsp-dart-test-tree-line-spacing The test tree line spacing between nodes 4
lsp-dart-main-code-lens Enable the Run\|Debug code lens on main methods. t
lsp-dart-test-code-lens Enable the Run\|Debug code lens on tests. t
lsp-dart-dap-extension-version The debugger extension version. 3.10.1
lsp-dart-dap-use-sdk-debugger Whether to use the debugger built-in on dart-sdk and not the node extension.version. t
lsp-dart-dap-debugger-path The debugger extension path Check source file
lsp-dart-dap-dart-debugger-program The command to execute the debugger extension on dart projects. Check source file
lsp-dart-dap-dart-test-debugger-program The command to execute the test debugger extension on dart projects. Check source file
lsp-dart-dap-flutter-debugger-program The command to execute the debugger extension on flutter projects. Check source file
lsp-dart-dap-flutter-test-debugger-program The command to execute the test debugger extension on flutter projects. Check source file
lsp-dart-dap-debug-external-libraries Whether to enable the debug on external libraries nil
lsp-dart-dap-debug-sdk-libraries Whether to enable the debug on Dart SDK libraries nil
lsp-dart-dap-vm-additional-args Additional args for dart debugging VM when the debugging.
lsp-dart-dap-tool-args Arguments to be passed to the Dart or Flutter tool. ""
lsp-dart-dap-flutter-track-widget-creation Whether to pass –track-widget-creation to Flutter apps. Required to support 'Inspect Widget'. t
lsp-dart-dap-flutter-structured-errors Whether to use Flutter’s structured error support for improve error display. t
lsp-dart-dap-flutter-hot-reload-on-save When enabled, every buffer save triggers a lsp-dart-dap-flutter-hot-reload nil
lsp-dart-dap-flutter-hot-restart-on-save When enabled, every buffer save triggers a lsp-dart-dap-flutter-hot-restart nil
lsp-dart-devtools-theme The devtools theme when openning via lsp-dart-dap-open-devtools "dark"
lsp-dart-devtools-hide-options What to hide when openning DevTools via lsp-dart-dap-open-devtools debugger

Additional packages#

  • lsp-ui : Flycheck, documentation and code actions support.
  • lsp-treemacs : lsp-mode GUI controls implemented using treemacs.
  • company-capf : Completion back-end support.
  • hover.el : Tool to run flutter mobile apps from desktop without the need of an emulator.
  • flutter.el : Tool to run flutter binary as an inferior process and interact with it from Emacs.


❔ Emacs can't find my package, it keeps searching up until the dart root package folder.

🔹 Configure projectile to find the package pubspec.yaml and set the folder as project root:

(with-eval-after-load 'projectile
  (add-to-list 'projectile-project-root-files-bottom-up "pubspec.yaml")
  (add-to-list 'projectile-project-root-files-bottom-up "BUILD"))

❔ LSP :: No LSP server for dart-mode(check *lsp-log*).

🔹 Try to set the lsp-dart-sdk-dir to the Dart SDK dir installation or if you are using Flutter, <your-flutter-dir>/bin/cache/dart-sdk/.


All feedback and suggestions are very welcome!

You can open a issue or for a quick answer, send a message on Gitter.

Last update: May 20, 2024