emit schema when doing JSON output

build.js

@@ -10,19 +10,31 @@ const fs = require("fs");
 const path = require("path");
 const jsYaml = require("js-yaml");
 const plist = require("plist");
+const prettier = require("prettier");
 
 const srcFile = path.join(__dirname, "src", "qsharp.tmLanguage.yml");
 const grammarsDir = path.join(__dirname, "grammars");
 
-function build() {
+// JSON Schema for TextMate grammars. Emitted only into the JSON outputs (as the
+// first key)
+const JSON_SCHEMA = "https://raw.githubusercontent.com/martinring/tmlanguage/master/tmlanguage.json";
+
+async function build() {
     const text = fs.readFileSync(srcFile, "utf8");
     const grammar = jsYaml.load(text);
 
+    const jsonGrammar = { $schema: JSON_SCHEMA, ...grammar };
+
+    // format with Prettier's defaults
+    const jsonText = await prettier.format(JSON.stringify(jsonGrammar), {
+        parser: "json",
+    });
+
     fs.mkdirSync(grammarsDir, { recursive: true });
 
     fs.writeFileSync(
         path.join(grammarsDir, "qsharp.tmLanguage.json"),
-        JSON.stringify(grammar, null, "\t") + "\n"
+        jsonText
     );
 
     fs.writeFileSync(
@@ -38,10 +50,13 @@ function build() {
     if (fs.existsSync(testExtDir)) {
         fs.writeFileSync(
             path.join(testExtDir, "qsharp.tmLanguage.json"),
-            JSON.stringify(grammar, null, "\t") + "\n"
+            jsonText
         );
         console.log("Refreshed test-extension/qsharp.tmLanguage.json");
     }
 }
 
-build();
+build().catch((err) => {
+    console.error(err);
+    process.exit(1);
+});