Introduction

The problem

TypeScript classes often accumulate repetitive code: getters and setters, equals and toString, builders, null checks, and singleton wiring. Design-pattern scaffolding (factory registries, memoization) adds more of the same.

Java teams solve much of this with Project Lombok. TypeScript has decorators, but no single library that combines Lombok ergonomics with Gang-of-Four patterns and a clear codegen story.

The solution

lombok-typescript provides:

1. Decorators you attach to classes, fields, and methods
2. Runtime behavior where reflection is enough (@Singleton, @Memoize, @NonNull)
3. Codegen where generated methods and types are clearer (@Data, @Builder, @ToString)
4. A CLI (lombok-ts generate) that writes .lombok/ companion files next to your sources

flowchart TB
  subgraph source [Your source]
    UserTs["src/user.ts\n@Data @Builder"]
  end
  subgraph runtime [Runtime decorators]
    Singleton["@Singleton @Memoize @NonNull"]
  end
  subgraph codegen [Codegen]
    Generate["lombok-ts generate"]
    Companion[".lombok/src/user.lombok.ts"]
    Types[".lombok/src/user.lombok.d.ts"]
  end
  UserTs --> Generate
  Generate --> Companion
  Generate --> Types
  UserTs --> Singleton
  Companion --> Apply["applyAllGenerated()"]

Two decorator standards

Backend	Import	When
Legacy	lombok-typescript/legacy	experimentalDecorators: true (NestJS, TypeORM)
Stage 3	lombok-typescript/stage3	experimentalDecorators: false (TS 5.0+ native decorators)

The same decorator names work in both backends; pick one per project.

Next steps

• Getting started — install and first generated class
• Architecture — how runtime and codegen interact
• Decorator overview — reference for each decorator