Loci Syntax for VS Code

Syntax highlighting for the Loci DSL used to describe rules, data dependencies, and computation steps in Loci-based applications.

What this extension highlights

• Loci directives and declarations like $include, $type, type names, storage kinds (store, storeVec, param, Map, MapVec, blackbox, Constraint, etc.), and $rule forms (pointwise, singleton, apply, unit, default, optional, constraint, blackbox).
• Rule modifiers and helpers: constraint(...), conditional(...), option(...), inplace(...), parametric(...), comments(...), prelude/compute/postlude, Loci reduction tags ([Loci::Summation]), constants like EMPTY/UNIVERSE.
• $-prefixed variables (including $variable{n=0}) and Loci namespace calls (Loci::load_module, Loci::makeQuery, etc.).
• Comments (//, /* */), string and numeric literals, and the <-ci->, <-, -> arrows used in rule heads.
• Mixed Loci/C++: unmatched content falls back to the built-in C++ grammar, especially inside { ... } blocks.

Quick use

• Install the extension, open a .loci file, and confirm the status bar shows Loci DSL. Colors come from your theme; this extension provides scopes.
• If VS Code doesn’t auto-detect, switch the language mode to Loci DSL manually.

Customize Loci colors (manual theme override)

• Open user settings JSON: Preferences: Open User Settings (JSON) or edit:
  • Linux: $HOME/.config/Code/User/settings.json
  • macOS: $HOME/Library/Application Support/Code/User/settings.json
  • Windows: %APPDATA%\\Code\\User\\settings.json
• Add or merge:

"editor.tokenColorCustomizations": {
  "textMateRules": [
    {
      "scope": "keyword.control.rule-statement.loci",
      "settings": { "fontStyle": "bold" }
    },
    {
      "scope": "support.function.rule-kind.loci",
      "settings": { "fontStyle": "italic" }
    },
    {
      "scope": "entity.name.function.rule-output.loci",
      "settings": { "foreground": "#ffcc66" }
    },
    {
      "scope": "variable.parameter.rule-input.loci",
      "settings": { "foreground": "#82aaff" }
    }
  ]
}

• Adjust colors to taste. These scopes come from syntaxes/loci.tmlLanguage.json and override your theme for Loci files.

Rule anatomy (quick reference)

• $rule keyword and rule kind (pointwise, singleton, apply, unit, default, optional, constraint, blackbox).
• Rule head: outputs before the rightmost <-, inputs after it; the arrow is highlighted separately.
• Trailing modifiers: constraint(...), conditional(...), inplace(...), option(...), parametric(...), comments(...); markers like prelude, compute, postlude.

Example

$include "flowPsi.lh"

$type solution store<real> ;
$type stop_iter param<int> ;

$rule default(stop_iter) { $stop_iter = 1000 ; }

$rule pointwise(dtcfl<-dtmax) {
  $dtcfl = real($dtmax) ;
}

$rule apply(cl->qresidual<-qdot)[Loci::Summation],
  constraint(cl->geom_cells) {
  join($cl->$qresidual, $qdot) ;
}

---

Developer info (build, test, package)

• Prereqs: Node.js 20+ for vsce packaging/publishing, npm. Node 18 is enough for npm install and npm run compile, but npx @vscode/vsce package, login, and publish currently fail there with ReferenceError: File is not defined.
• Install deps: npm install
• Build once: npm run compile (or npm run watch while developing)
• Run in VS Code: open the folder, press Run and Debug (F5) and pick Run Extension; reload the Extension Development Host after edits. For a faster loop, run npm run watch in the main window while using F5 to reload.
• Package a VSIX (share/install locally):

npm install
npm run compile
npx @vscode/vsce package

• Outputs loci-syntax-<version>.vsix; install via code --install-extension loci-syntax-*.vsix.
• If vsce warns about a missing repository field, add your Git repo URL to package.json or pass --allow-missing-repository.

Publish to Marketplace

• Publisher for this repo: StreamlineNumerics (see package.json).
• Before publishing, bump the extension version in package.json.
• Use Node.js 20+ for the publish step. Current @vscode/vsce in this repo declares node >= 20, and Node 18 fails during vsce login/package/publish.
• Create or confirm a Visual Studio Marketplace publisher named StreamlineNumerics.
• Create an Azure DevOps personal access token with Marketplace Manage permission.
• Log in once on this machine:

npx @vscode/vsce login StreamlineNumerics

• Publish a new version directly:

npm install
npm run compile
npx @vscode/vsce publish

• Or publish while bumping the version automatically:

npx @vscode/vsce publish patch

npx @vscode/vsce publish minor

npx @vscode/vsce publish major

• If you prefer uploading through the website instead of direct CLI publish:

npm install
npm run compile
npx @vscode/vsce package

• Then upload the generated .vsix at https://marketplace.visualstudio.com/manage/publishers/.
• Official docs: https://code.visualstudio.com/api/working-with-extensions/publishing-extension

Contributing

• Adjust scopes in syntaxes/loci.tmlLanguage.json.
• Update language-configuration.json if bracket or comment behavior changes.
• Provide example snippets/screenshots in this README to showcase improvements.

Release Notes

• 0.1.0 — Expand grammar coverage, add language activation, and document install/usage.
• 0.0.1 — Initial scaffold.