Prettier - Code Formatter
_{Wolfram Language for VS Code}

Format Wolfram Language files in VS Code with Prettier and @wrel/prettier-plugin-wolfram.

Features · Install · Usage · Settings · Troubleshooting

The extension registers the wolfram language, provides document and range formatting, validates Wolfram-specific Prettier options in JSON .prettierrc files, and reports formatter-backed diagnostics with Quick Fix actions.

Highlights

Features

• Formats .wl, .wls, .wlt, .m, .mt, .nb, and .cdf files assigned to the wolfram language.
• Supports VS Code Format Document, Format Selection, Format Document With..., and format-on-save workflows.
• Maps selection formatting to complete top-level Wolfram expressions touched by the selection.
• Shows diagnostics for formatter-fixable rule findings and formatting diffs.
• Provides lightbulb Quick Fix actions to format the current diagnostic range or the whole document.
• Resolves Prettier configuration with EditorConfig support from the current workspace file.
• Adds JSON validation, autocomplete, and hover descriptions for Wolfram Prettier options in .prettierrc, .prettierrc.json, and .prettierrc.json5.
• Prefers workspace-installed prettier and @wrel/prettier-plugin-wolfram, then falls back to the bundled copies.
• Reuses the plugin's shared Wolfram kernel helper across CLI and editor requests.

Requirements

• VS Code 1.75 or newer
• Node.js available on PATH
• A local Wolfram Engine or Mathematica installation with CodeParser
• WolframKernel discoverable automatically, or an explicit Wolfram engine path

The extension bundles Prettier and the Wolfram Prettier plugin. Parsing still requires a local Wolfram runtime.

If VS Code cannot find node, set WOLFRAM_NODE_PATH to a Node.js executable before launching VS Code.

Install

Install from the VS Code Extensions view by searching for:

Prettier - Code formatter (Wolfram Language)

For manual installation, install a packaged .vsix:

1. Run Extensions: Install from VSIX... in VS Code.
2. Select wolfram-prettier-vscode-<version>.vsix.

No workspace npm install is required for a packaged extension.

Usage

Open a Wolfram file and run one of VS Code's standard formatting commands:

• Format Document
• Format Selection
• Format Document With..., then choose this formatter if multiple formatters are installed

To format on save:

{
	"[wolfram]": {
		"editor.defaultFormatter": "Tone.wolfram-prettier-vscode",
		"editor.formatOnSave": true
	}
}

Range formatting formats complete top-level expressions that intersect the selection. If the selection cannot be mapped safely, no edit is returned.

Extension Settings

This extension contributes these VS Code settings:

{
	"wolframPrettier.wolframEnginePath": "",
	"wolframPrettier.diagnosticSeverity": "information",
	"wolframPrettier.cstRequestTimeoutMs": 180000
}

Use wolframPrettier.wolframEnginePath for editor-only setup. Use the Prettier option wolframEnginePath when the same path should also apply to CLI formatting.

After changing wolframPrettier.wolframEnginePath, reload the VS Code window so the extension can restart with the updated environment.

wolframPrettier.cstRequestTimeoutMs supplies the editor default for formatter requests. A wolframCSTRequestTimeoutMs value in the resolved Prettier config takes precedence for that file.

Prettier Configuration

The extension resolves Prettier configuration from the current file's workspace with EditorConfig enabled and cache disabled, so .prettierrc edits are picked up immediately.

It passes parser: "wolfram" automatically and appends the resolved Wolfram plugin to any configured plugins list. You do not need to add the plugin only for VS Code formatting, but keeping it in .prettierrc is useful when the same project is formatted from the CLI.

Complete .prettierrc example:

{
	"plugins": ["@wrel/prettier-plugin-wolfram"],
	"printWidth": 80,
	"tabWidth": 2,
	"wolframNewlinesBetweenDefinitions": 1,
	"wolframMaxBlankLinesBetweenCode": 1,
	"wolframSpaceAfterComma": true,
	"wolframSpaceAroundOperators": true,
	"wolframAlignRuleValues": false,
	"wolframDocumentationCommentColumn": 0,
	"wolframDocumentationCommentPadding": 2,
	"wolframTopLevelSpacingMode": "declarations",
	"wolframPreserveTildeInfixFunctions": "",
	"wolframCSTRequestTimeoutMs": 180000,
	"wolframModuleVarsBreakThreshold": 40,
	"wolframConditionFirstFunctions": "If,Switch",
	"wolframBlockStructureFunctions": "Module,With,Block,DynamicModule",
	"wolframCaseStructureFunctions": "Which",
	"wolframEnginePath": "",
	"wolframLintRules": "{}"
}

Use Prettier's standard printWidth, tabWidth, useTabs, endOfLine, and related options for core Prettier behavior.

Wolfram Option Reference

wolframTopLevelSpacingMode has these values:

Diagnostics And Quick Fixes

Diagnostics are formatter-backed hints, not a full language server. They run for local file-backed Wolfram documents after open, change, and save events.

The extension reports:

• formatter-fixable rule findings such as spacing, line width, top-level blank-line spacing, and general infix normalization
• formatting diffs where the formatted document would change whitespace, wrapping, comments, or related style details

Diagnostics ignore changes that are only a final newline difference. Quick Fixes can apply formatting to the diagnostic range or to the whole document.

The global squiggle severity comes from wolframPrettier.diagnosticSeverity. Supported values are information, warning, hint, and error.

Runtime Resolution

For each file, the extension resolves formatter dependencies in this order:

1. A direct workspace dependency on prettier, otherwise bundled Prettier.
2. A plugin checkout when the workspace package is @wrel/prettier-plugin-wolfram or prettier-plugin-wolfram.
3. A direct workspace dependency on @wrel/prettier-plugin-wolfram or prettier-plugin-wolfram.
4. The bundled Wolfram plugin.

This lets editor formatting match CLI formatting when the project installs its own Prettier and plugin versions, while still working in projects with no local Node dependencies.

File Associations

The extension contributes the wolfram language for these extensions:

.wl .wls .wlt .m .mt .nb .cdf

Formatting expects text Wolfram Language source. Binary or notebook-structured files should not be formatted as plain text.

To format another custom extension, add a VS Code file association:

{
	"files.associations": {
		"*.wlx": "wolfram"
	}
}

Troubleshooting

WolframKernel not found: Set wolframPrettier.wolframEnginePath, set wolframEnginePath in Prettier config, set WOLFRAM_ENGINE_PATH, or make sure WolframKernel is available on PATH.

Node.js not found in PATH: Install Node.js and make it available on PATH, or set WOLFRAM_NODE_PATH to the Node.js executable before starting VS Code.

Formatting does not run: Make sure the file language mode is Wolfram and select this extension with Format Document With... if another formatter is installed.

Diagnostics do not appear immediately: Diagnostics run after documents open, change, or save. Large files and cold Wolfram startup can delay the first result.

Config changes are not reflected: The extension disables Prettier's config cache for resolution, but VS Code may need the file to be reformatted or diagnostics to refresh after an edit.

More detail: Open the Prettier (Wolfram) output channel.

Development

From the repository root, build the standalone extension package with:

npm run package:vscode:standalone

This writes vscode-extension/wolfram-prettier-vscode-<version>.vsix.

For Marketplace pre-release publishing from the repository root:

npm run publish:vscode:pre-release