ReScript VSCode

The Official VSCode plugin for ReScript

Contents

• 📝 Prerequisite
• 🌈 Supported Themes
• 💡 Features
• 📥 Installation
• 📦 Commands
• 🔨 Settings
• 🚀 Code Analyzer
  • Configuring the Code Analyzer
  • Usage
  • Caveats
• 🪄 Tips & Tricks
  • Hide generated files
• ⌨️ Use with Other Editors
• 📰 Changelog
• 👏 How to Contribute
• 📄 License

📝 Prerequisite

You must have ReScript >= 9.1 installed locally in your project, through the usual npm or yarn installation. Older versions are not guaranteed to work.

🌈 Supported Themes

Our highlighting works well with most popular VSCode themes, such as:

• Dark+ (default dark), Light+ (default light)
• Solarized Dark, Solarized Light
• Monokai Dimmed
• Tomorrow Night Blue
• One Dark Pro

The only 2 themes we don't (and can't) support, due to their lack of coloring, are:

• Dark (Visual Studio), Light (Visual Studio)

Note If your custom theme doesn't seem to highlight much (e.g. no colors for upper-case JSX tag, no distinction between module and variant), try one of the recommended themes to see if that's the problem. For more info, see this post.

💡 Features

• Supports .res, .resi and bsconfig.json.
• Syntax highlighting.
• Formatting.
• Build diagnostics.
• Built-in bsb watcher (optional, and exposed explicitly as a pop-up; no worries of dangling build).
• Type hint hover.
• Jump to definition.
• Autocomplete.
• Find references.
• Rename.
• Inlay Hints.
• Signature help.
• Code lenses.
• Snippets to ease a few syntaxes:
  • external features such as @bs.module and @bs.val
  • try, for, etc.
• Folding, and custom folding through //#region and //#endregion.

📥 Installation

Launch VS Code Quick Open (Ctrl+P), paste the following command, and press enter.

ext install chenglou92.rescript-vscode

The plugin activates on .res and .resi files. If you've already got Reason-Language-Server installed, it's possible that the latter took precedence over this one. Make sure you're using this plugin ("ReScript syntax") rather than Reason-Language-Server ("BuckleScript syntax").

Pre-release channel

There is a pre-release channel available. It is intended for testing new and therefore possibly unstable features. You can activate it by clicking on the "Switch to Pre-Release Version" button on the rescript-vscode extension page in VSCode. From this point on, pre-release versions will always have an odd version minor (1.5.x, 1.7.x, 2.1.x, etc.) while stable releases have even version minor numbers (1.4.x, 1.6.x, 2.0.0, etc.).

Even if the pre-release channel seems too experimental to you, we still suggest you to give it a try and submit any issues that you run into. In the long run it will give us a better editor experience overall.

📦 Commands

🔨 Settings

You'll find all ReScript specific settings under the scope rescript.settings.

Default settings:

// Whether you want the extension to prompt for autostarting a ReScript build if a project is opened with no build running
"rescript.settings.askToStartBuild": true,

// Automatically start ReScript's code analysis.
"rescript.settings.autoRunCodeAnalysis": false,

// Path to the directory where cross-platform ReScript binaries are. You can use it if you haven't or don't want to use the installed ReScript from node_modules in your project.
"rescript.settings.binaryPath": null

// Path to the directory where platform-specific ReScript binaries are. You can use it if you haven't or don't want to use the installed ReScript from node_modules in your project.
"rescript.settings.platformPath": null

// Enable (experimental) inlay hints.
"rescript.settings.inlayHints.enable": true

// Maximum length of character for inlay hints. Set to null to have an unlimited length. Inlay hints that exceed the maximum length will not be shown
"rescript.settings.inlayHints.maxLength": 25

// Enable (experimental) code lens for function definitions.
"rescript.settings.codeLens": true

🚀 Code Analyzer

The Code Analyzer is a mode in the extension that runs additional code analysis in your project. The analysis helps you find dead code at a granular level, find unhandled exceptions, and more.

The Code Analyzer uses reanalyze, which is embedded in the extension, so you don't need to install anything extra to run it.

Configuring the Code Analyzer

You'll need to configure what code analysis you want to run, and what (if any) directories you want to ignore. Configuration is done via adding reanalyze in bsconfig.json. You'll get autocomplete for what configuration options are valid. You can also read all about configuring reanalyze here.

Usage

Open the command palette and run ReScript: Start Code Analyzer. This will start code analysis in the ReScript project of the file you run the command from.

Dead code is highlighted in the editor, and code actions for suppressing dead code warnings are available in most cases.

When done, stop the code analysis mode by clicking the Stop Code Analyzer button in the editor status bar. This will clear all reported analysis warnings.

Caveats

Currently does not work for full monorepo dead code analysis (although it should work for each monorepo package individually).

🪄 Tips & Tricks

Hide generated files

You can configure VSCode to collapse the JavaScript files ReScript generates under its source ReScript file. This will "hide" the generated files in the VSCode file explorer, but still leaving them accessible by expanding the source ReScript file they belong to.

Open your VSCode settings and type:

"explorer.fileNesting.enabled": true,
"explorer.fileNesting.patterns": {
  "*.res": "${capture}.mjs, ${capture}.js, ${capture}.cmi, ${capture}.cmt, ${capture}.cmj",
  "*.resi": "${capture}.res"
},

This nests implementations under interfaces if they're present and nests all generated files under the main ReScript file. Adapt and tweak to your liking.

A screenshot of the result:

⌨️ Use with Other Editors

This repo also contains a language server that can power other editors. However, the language server in this project is a pure implementation detail. We don't guarantee its stability for other editors' consumption apart from Vim and Sublime Text.

Still, if you'd like to use this language-server with other editors:

• Get the release binaries from the Github Releases page.
• Unzip the .vsix and get the server folder. That's the only folder you need.
• The language server will be at server/out/server.js. Call it through node, and optionally pass --stdio if your editor doesn't support the default JSONRPC.

📰 Changelog

See CHANGELOG

👏 How to Contribute

Read our Contributing Guide

📄 License

See the LICENSE file for details.