Introduction

What is OOFP?

OOFP (Object-Oriented Functional Programming) is a TypeScript library ecosystem for building type-safe applications using functional programming patterns. It provides algebraic data types, composition utilities, and real-world patterns that scale from small utilities to large production applications.

The Problem

TypeScript applications commonly suffer from:

• Untyped errors — try-catch loses type information about what can go wrong
• Implicit dependencies — Functions reach into global state or closures for their dependencies
• Nullable chaos — null and undefined propagate silently through code
• Callback hell — Async operations become deeply nested and hard to follow

The Solution

OOFP provides algebraic data types that make these problems impossible:

Problem	OOFP Solution	Type
Nullable values	Maybe — values that may or may not exist	Maybe<A>
Operations that can fail	Either — typed success or failure	Either<E, A>
Async operations	Task — lazy async computation	Task<A>
Async + failure	TaskEither — async that can fail	TaskEither<E, A>
Dependency injection	Reader — function that needs context	Reader<R, A>
DI + async + failure	ReaderTaskEither — the ultimate monad	RTE<R, E, A>

Design Principles

1. Type safety first — No any, no type assertions, full inference
2. Composition over inheritance — Everything composes with pipe and flow
3. Laziness — Computations describe what to do, not when to do it
4. Execute at boundaries — Build pure pipelines, run them at HTTP handlers or CLI entry points
5. Zero dependencies — No runtime dependencies, tree-shakeable imports

Ecosystem

OOFP is a monorepo with 5 packages:

• @oofp/core — Foundation: all monads, composition, collections, type classes
• @oofp/http — HTTP client built on ReaderTaskEither
• @oofp/query — Query cache with TTL and invalidation
• @oofp/saga — Saga pattern for transactional workflows
• @oofp/react — React hooks (experimental)

Inspiration

OOFP is inspired by fp-ts and the Fantasy Land Specification, with a focus on practical usability and real-world patterns over theoretical purity.