Chuchu Language for VS Code

Language support for Chuchu, built against its current assign … as and function … be syntax. Requires VS Code 1.96 or newer.

Features

• .chuchu file recognition and TextMate syntax highlighting for keywords, numeric literals, strings, escapes, comments, types, results, built-ins, and functions.
• Comment toggling, bracket matching, automatic pairs, indentation, and folding.
• Snippets for declarations, reassignment, functions, conditionals, loops, input, and result handling.
• Completions for keywords, types, all current built-ins, and visible document symbols.
• Hover documentation and function signature help, including nested calls and err<T>(code).
• Go to Definition, Find All References, occurrence highlighting, and document outline.
• Live lexical diagnostics for invalid characters, escapes, strings, numeric literals, comments, and unmatched delimiters.
• Build commands using Cheeku, with compiler errors in the Problems panel.

Navigation understands block shadowing, declaration order, parameter scope, forward function calls, and functions that cannot capture top-level variables. Language features run locally in the extension host and work without an installed compiler.

Install

Download or build chuchu-vscode.vsix, then select Extensions → … → Install from VSIX… in VS Code. Alternatively:

code --install-extension chuchu-vscode.vsix

Open any .chuchu file. See examples/features.chuchu for a sample.

Build a program

Build Cheeku from source with its host toolchain. The compiler does not need a published release; point the extension at the executable produced by your local build.

For sibling checkouts of chuchu-core and chuchu-vscode, opening chuchu-vscode in VS Code uses the checked-in .vscode/settings.json:

{
  "chuchu.compilerPath": "../chuchu-core/target/release/cheeku"
}

When opening the parent chuchu-org folder instead, set chuchu.compilerPath to ./chuchu-core/target/release/cheeku in that folder's .vscode/settings.json. For a different workspace or a standalone file, use the absolute path to your local compiler. To use a debug compiler build, replace target/release with target/debug. A release compiler can produce both normal and debug programs.

On Windows, append .exe to the compiler filename, or use an escaped path such as "C:\\tools\\cheeku.exe". Supply only the executable path, without surrounding shell quotes or extra arguments. Paths containing directories are resolved relative to the file's workspace folder, or its source directory when no workspace folder is open. A bare name is resolved through PATH.

Open a saved .chuchu file and use the editor's build button or the Command Palette:

• Chuchu: Build Current File compiles with -O2.
• Chuchu: Build Current File for Debugging compiles with --debug (O0 and native debug information).

The command saves pending edits and writes the executable to .chuchu/build/<source-name> beside the source file, with a -debug suffix for debug builds and .exe on Windows. Add .chuchu/ to your project's .gitignore. The terminal shows compiler output; located compiler errors also appear in Problems. Run the compiled executable in your terminal. Native debugging requires an appropriate debugger extension and launch configuration; see Chuchu's debugging guide.

Build commands require a trusted workspace and a local filesystem. Editing features are available in Restricted Mode and virtual workspaces. Compiler execution uses a process task with separate arguments, so file paths are passed directly without shell interpolation.

Settings and current limits

The editor analyzer tolerates incomplete code. It does not implement Cheeku's complete parser, type checker, or runtime checks. Build for authoritative syntax and type diagnostics. Inferred variables are labeled “inferred by Cheeku”; the extension does not guess their types. Navigation is limited to the current document, matching Chuchu's current lack of modules/imports. Automatic formatting, rename, and a bundled debugger are not included.

Develop and verify

Use Node.js 22 or newer:

npm ci
npm test
npm run test:integration
npm run package

Open this repository in VS Code and press F5 to launch an Extension Development Host. The compile task runs before launch. npm run watch recompiles during development.

npm test verifies scope resolution, shadowing, UTF-16 source offsets, incomplete code, nested call arguments, actual TextMate tokenization, and compiler problem matching. npm run test:integration downloads VS Code 1.96.0 and exercises the registered providers in its extension host. Set VSCODE_VERSION=stable to check the current stable version. Linux CI runs this command under Xvfb. Set CHUCHU_COMPILER to an installed Cheeku executable to also test release/debug builds, dirty-file saving, paths with spaces, and compiler diagnostics end to end.

npm run package produces chuchu-vscode.vsix. The package has no production npm dependencies and contains the compiled extension, grammar, language configuration, snippets, documentation, and license. Packaging does not publish it to the Marketplace. Marketplace publication requires a verified chuchu-lang publisher account.

The editor providers use the VS Code language feature API.