Validation

ROSETTA STONE

Planned

ROSETTA 21 — Implementation Comparison
Compare defensive validation and fallback behavior across languages.

Rosetta Stone Validation Preview coming soon

ROSETTA 21

Rosetta Stone Validation

Comparison Contract

Accept valid input and return safe controlled output for invalid input.

Comparison Contract

Accept valid input and return safe controlled output for invalid input.

Objective & Comparison Rule

Build each implementation without changing the shared behavior or visual target.

Rosetta Contract

Objective

Compare defensive validation and fallback behavior across languages.

Comparison Rule

Accept valid input and return safe controlled output for invalid input.

Keep equivalent input, behavior, and visible output in every later language version.

Implementation Plan

Keep the comparison surface fixed while language syntax and runtime details change.

Structure

project/
├── input/
│   └── fixture.json
├── expected/
│   └── output.json
├── package.json
├── tsconfig.json
├── index.html
├── styles.css
└── src/
    └── app.ts

Initial Implementation

JavaScript / modern ECMAScript
HTML
CSS

Comparison Languages

JavaScript / modern ECMAScript
TypeScript
Angular
Python
Java
C#
PHP

Source Learning Project

Source Learning Project — TypeScript Lab: Safe JSON Metadata Parser

src/local-editor/server.ts → parseMetadata()

Technologies

JavaScript / modern ECMAScript

TypeScript

Angular

Python

Java

PHP

Build Instructions

Start with the first technology listed under Technologies, then reproduce the same behavior in each following implementation.

Freeze the Contract

Define the exact input, visible behavior, and expected output.

Build Initial Implementation

Implement the reference version with the same standalone visual layer.

Later Comparison

Rebuild without changing the contract.

TypeScript Implementation Reference

This implementation becomes the first concrete Rosetta comparison point.

Reference Code

Use the same input when building later language versions.

function parseMetadata(value: unknown): Record<string, unknown> {
  try {
    const parsed = JSON.parse(String(value));
    return parsed && typeof parsed === "object" && !Array.isArray(parsed)
      ? parsed
      : {};
  } catch {
    return {};
  }
}

TypeScript Implementation Configuration

Keep the TypeScript implementation independently buildable; each implementation should keep its own required setup.

package.json

{
  "type": "module",
  "scripts": { "build": "tsc" },
  "devDependencies": { "typescript": "^7.0.2" }
}

tsconfig.json

{
  "compilerOptions": {
    "rootDir": "./src",
    "outDir": "./dist",
    "target": "ES2022",
    "module": "ES2022",
    "lib": ["ES2022", "DOM"],
    "strict": true,
    "sourceMap": true
  },
  "include": ["src/**/*.ts"]
}

Comparison Dimensions

Record differences that teach language and runtime behavior rather than cosmetic syntax.

Compare

Syntax and data declarations
Typing and validation
Collections and standard-library operations
Modules and file organization
Runtime and build requirements
Database or HTTP APIs when applicable
Visible output and behavioral equivalence