samuelematias/howtoclojuredart

Live article on ClojureDart development introduction

Introduction

April 16th, the ClojureDart release day, and the meaning of this is crucial. Clojure devs are now able to write mobile, web and desktop apps with Flutter.

Currently, tools are not yet ready to go full speed. There is no REPL(!) and no dart-interop autocompletion, but it is still usable. Also, some of the Clojure magic is being shown already, for example, check the nest macro and compare similar clj-code vs dart.

The goal of this article is to show how to write your first Flutter app with Clojure, what tools to use, and where to ask questions. The reader should keep in mind that minor clojure experience is required.

The tools

For the ClojureDart journey you would need to set up Flutter on your machine, Clojure cli, and additionally I would recommend Clj-kondo. The last would be helpful for widget macro warnings:

Choose your the editor

VSCode — easy to start

I am not a VSCode user, but as far as I know, it's the easiest option to start. Just install Calva, and you are ready to go:

vscode-calva.mp4

I would also recommend installing the Flutter extension (docs).

Pros:

• fast and easy to set up;
• unique Joyride plugin, that allows to run editor scripts with Clojure REPL.

Intellij Idea — no support yet

The result you would get (typing reduce- to show clojure-autocompletion):

As you see, there are warnings on dart-interop, and it's impossible to get rid of them without turning on "Power Safe Mode".

Pros:

• almost nothing to set up;
• support will be there, and everything will get to work.

Cons:

• Extremely slow startup (could be more than 1 minute until syncing, indexing, resolutions, etc. is completed on my air);
• No way to turn off dart-interop warnings.

Anyway, for setting the Idea up you would need 3 things: Cursive plugin. Flutter plugin (to be able to search through the dart code). Clojure-extras plugin (for Clj-kondo linting support).

Also don't forget to set up \*.cljd files as Clojure files: preferences -> editor -> filetypes -> clojure file -> file patterns -> + -> \*.cljd

Vim

Same example with reduce-:

Pros:

• speed, the ability to open tens (and hundreds) of projects at the same time in milliseconds;
• extended customization;
• REPL will be integrated out of the box with ClojureDart REPL release;
• the ability to write config in Lisp (Fennel).

Cons:

• need to learn how to use vim;
• need to spend some time on setting everything up;
• sometimes need to fix things after updates.

Below there are several options on how to set up Vim for ClojureDart.

Nvim with lsp

Need to set up a lsp-plugin and 2 lsp servers: for Clojure and for Flutter (for the ability to search through the dart code). Need to add one line to set up *.cljd:

au! BufRead,BufNewFile *.cljd setfiletype clojure

I am using this config at the moment and besides dart-interop there are almost everything: refactorings, goto definition, find usages, autocompletion, docs, namespace cleaning.

My config is written in Fennel. Going through this is out of the scope of this article. If you want to try using Lisp for configuration yourself, I would recommend starting with aniseed plugin and the authors dotfiles. As the first config you could use this project or try nyoom setup.

Vim with the VimIced plugin

You would need to set up everything with the plugin's wiki and use Clj-Kondo as the linter (use this instruction). Until ClojureDart REPL is released, lots of features will not be supported.

Vim with Fireplace

I haven't used Fireplace recently (last 3 years). I guess the experience will be somewhat of VimIced. Be sure to write:

au! BufRead,BufNewFile *.cljd setfiletype clojure

Emacs

ClojureDart authors are using Emacs, and Clojure-mode has already added cljd (don't need to do anything yourself). I think the pros and cons will be similar to vim, with some details that are out of the scope.

The workflow

Good to start with the hello-world and get comfortable with the tools.

Then I would open 3 windows:

1. Dart file (could be a \*.dart file inside lib/ directory) to be able to experiment with dart code, to check signatures, fields and methods.
2. Terminal to see the logs and to interact with the hot-reload;
3. Emulator, in my experience Android is the good one. The easiest way to set up one is to install AndroidStuod and use Tools->DeviceManagement.

After you launch a watcher:

clj -M -m cljd.build flutter

Go to the loop: write code, save file, see feedback, repeat.

• Need a hot-reload, save file.
• Need a hot-restart, press Enter in the terminal.
• Need to cold-reborn, remove .clojuredart/ dir and restart the watcher.

Using Libraries

As in the Flutter project, add libs in the pubspec.yaml file. Import it as a string like you would in the *.dart files:

(:require
    [clojure.string :refer [join]]
    ["package:graphql/client.dart" :as g])

And currently it's impossible to import a dart class without having it as a dependency in pubspec.yml.

Building widget tree approach

In most of the cases you should write a function like here in the authors' examples; and not declare a class with deftype like I did here. And StatefulWidgets should be created with the alpha/widget macro.

ClojureDart differs from Clojure

First, consider reading the docs from authors upon the subject.

Next, you would definitely stumble upon the lack of libraries that return plain old Clojure PersistentHashMap. Instead you will have to deal with dart Maps. Here in the GraphQL example I wrote a function to convert dart Map into clojure PersistentHashMap.

Resources

1. Official docs on ClojureDart
2. Samples by the authors
3. GraphQL + MVU sample
4. Custom widgets with deftype sample
5. Community: Clojurians channel, #clojuredart
6. Twitter разработчиков: cgrand, BaptisteDupuch