Awsum language support for Visual Studio Code

VS Code extension for the Awsum programming language (.aww files). A thin LSP client to the awsum lsp server bundled with the Awsum compiler — every diagnostic, code action, format edit, document symbol, and workspace symbol is computed inside the awsum compiler binary and pushed over LSP.

Features

Syntax highlighting — TextMate grammar for .aww files.
Format on save — textDocument/formatting, triggered by the standard editor.formatOnSave setting (enabled by default for the awsum language via contributes.configurationDefaults in package.json).
Inline diagnostics — textDocument/publishDiagnostics, pushed on open / save / change (debounced 500 ms server-side). error vs warning severity honoured by the VS Code Problems panel.
Quick fixes (lightbulb) — textDocument/codeAction. Compiler-supplied fixes only; the extension does no language-aware reasoning.
Document outline — textDocument/documentSymbol. Drives the Outline panel, breadcrumbs, and Ctrl+Shift+O symbol search.
Workspace symbol search (Ctrl+T) — workspace/symbol. The server walks every .aww under the workspace folders received at initialize.

Install

Install the Awsum compiler (see awsum-lang/awsum) and ensure awsum is on your PATH.
Install the extension from the Visual Studio Marketplace or the Open VSX Registry. For a locally-built .vsix: Cmd+Shift+P → Extensions: Install from VSIX….

If awsum is not on your PATH, point the extension at the binary via Settings → awsum.path (e.g. /usr/local/bin/awsum). A change to this setting restarts the LSP client automatically — no editor reload needed.

Commands

Command	Default keybinding	What it does
`Awsum: Restart Awsum LSP server`	—	Stops the `awsum lsp` process and starts a new one with the same settings. Useful after a local `stack install` of a new `awsum` build, or to clear any in-memory state on the server.

Bind it to a keybinding via the standard VS Code Keyboard Shortcuts editor (awsum.restartLspServer).

Versioning

awsum-vscode A.B.C is built and tested against awsum A.B.C. Mismatched versions are not supported — at startup the LSP server compares the extension's expected version against its own and shows a non-blocking notification on mismatch.

Visual Studio Marketplace only accepts plain semver A.B.C (no 4th segment, no pre-release tags), so we can't iterate the extension independently under a fixed compiler version. Every awsum release ships a matching extension release (minimum once); the extension is never released ahead of the compiler. Only the latest awsum release is supported.

Development

npm i               # install dependencies
npm run compile     # type-check via tsc
npm run bundle      # esbuild → dist/extension.js
npm run package     # bundle + vsce package → awsum-vscode-A.B.C.vsix

Structure

src/extension.ts                # LSP client (vscode-languageclient → awsum lsp)
syntaxes/awsum.tmLanguage.json  # TextMate grammar
language-configuration.json     # Comment / bracket / auto-close config
dist/extension.js               # Bundled output (esbuild)

Architecture

Single source of truth. awsum-vscode does no language-aware processing. All semantics live in awsum/src/Awsum/Lsp.hs (the LSP server) and the modules it reuses (Awsum.Diagnostic, Awsum.Symbols, Awsum.Format, Awsum.ElaborateLower, …).
No custom providers. Everything routes through vscode-languageclient standard handlers. Anything you'd want to add for VS Code is best added on the LSP server side first — that way awsum-zed, Helix, and any other LSP client benefit too.

Compiler: awsum-lang/awsum
Zed extension: awsum-lang/awsum-zed
Tree-sitter grammar: awsum-lang/tree-sitter-awsum
Examples: awsum-lang/awsum-examples
Website: awsum-lang.org

AI use

This VSCode extension is developed with substantial usage of generative AI. Every generated change is reviewed, edited, and accepted by a human before it lands in the repository, and no output is shipped unedited.

License

Apache 2.0 — see LICENSE and NOTICE.

Awsum