Add structural comparison

website/src/playground/files/index.ts

@@ -11,6 +11,7 @@ export const orderedFiles = [
   "/tutorial/revertOnCatch.ts",
   "/tutorial/strings.ts",
   "/tutorial/const.ts",
+  "/tutorial/structuralComparison.ts",
   "/tutorial/binaryTree.ts",
   "/tutorial/specialFunctions.ts",
   "/tutorial/treeShaking.ts",

website/src/playground/files/root/tutorial/structuralComparison.ts

@@ -0,0 +1,22 @@
+// Also due to value semantics, arrays and objects are compared on their content instead of their
+// identity.
+
+export default function () {
+  return vec3(-5, 7, 12) === vec3(-5, 7, 12);
+  // JavaScript:  false
+  // ValueScript: true
+}
+
+function vec3(x: number, y: number, z: number) {
+  return { x, y, z };
+}
+
+// Caveat:
+// - TypeScript will emit an error for expressions like `[a, b] === [c, d]`.
+//
+// This is unfortunate. It's to protect you from accidentally expecting structural comparison in JS,
+// but in ValueScript, that's exactly how it *does* work.
+//
+// ValueScript will still happily evaluate these expressions (ValueScript doesn't use the TS
+// compiler), but you might want to rewrite these expressions as `eq([a, b], [c, d])` until
+// dedicated ValueScript intellisense is available.