📦 Server-Side Application Example — TypeScript + DDD + Functional Programming

This repository provides an example of how to build a server-side application using TypeScript, following Domain-Driven Design (DDD) principles combined with a functional programming approach.

The project follows a package-by-feature architecture, where each feature encapsulates its own domain, DTOs, controllers, and handlers. Currently, the repository includes the Users module as a reference implementation.

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🚀 Technologies & Concepts Used

• TypeScript — static typing for safer, predictable development
• Domain-Driven Design (DDD) — clear domain boundaries and domain-focused code organization
• Functional Programming — pure functions, immutability, and explicit data transformations
• Package-by-Feature Architecture — features grouped by domain instead of technical layers

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🧱 Project Structure

The project structure is organized by domain feature. Here is the current structure based on the Users module:

src/
└── Modules/
    ├── SeedWork/
    │   └── ...shared domain utilities, base types
    │
    └── Users/
        ├── Controllers/
        │   └── ...HTTP controllers for user routes
        │
        ├── Domain/
        │   └── ...entities, value objects, Derivers, Invariants
        │
        ├── DTOs/
        │   └── ...data transfer objects used across use cases and controllers
        │
        └── Handlers/
            └── ...application handlers

This layout isolates each module’s responsibilities while keeping domain logic separate from HTTP and application-level code.

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📥 Installation

npm install
# or
yarn install

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▶️ Running the Application

Development:

npm run dev

🧪 Testing

npm test

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🎯 Purpose of This Example

This repository aims to demonstrate:

• Practical application of DDD in TypeScript
• How functional programming helps reduce side effects and increase predictability
• How to structure server-side applications using package-by-feature
• A complete reference of a feature module (Users)