Arrays and Collections

ROSETTA STONE

Planned

ROSETTA 03 — Implementation Comparison
Compare typed collections and iteration across languages.

ROSETTA 03

Rosetta Stone Arrays and Collections

Array or collection declarations, insertion, iteration, and rendering.

Objective & Comparison Rule

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

Rosetta Contract

Objective

Compare typed collections and iteration across languages.

Comparison Rule

Array or collection declarations, insertion, iteration, and rendering.

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

Technologies

JavaScript / modern ECMAScript

TypeScript

Typed browser implementation that keeps the JavaScript behavior while adding compile-time models and checks.

Angular

Python

Backend/API implementation that models, filters and serves the same agenda output with Python.

Java

Java backend implementation

C# backend implementation

PHP

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
JSON

Comparison Languages

JavaScript / modern ECMAScript
TypeScript
Angular
Python
Java
C#
PHP

Source Learning Project

Source Learning Project — TypeScript Lab: Typed Arrays Gallery

src/datastore/types.ts

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.

type Technology = { name: string };

const technologies: Technology[] = [
  { name: "TypeScript" },
  { name: "SQLite" },
];

technologies.push({ name: "HTML" });

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