@oofp/core

@oofp/core is the foundation of the OOFP ecosystem. It provides algebraic data types, function composition utilities, collection helpers, type classes, and a Higher-Kinded Types system — all with zero runtime dependencies.

pnpm add @oofp/core

License: MIT | Zero dependencies | Tree-shakeable — import only what you use.

---

Monads

The core data types for modeling effects in your programs.

Module	Import	Description
Maybe	@oofp/core/maybe	Optional values without null or undefined
Either	@oofp/core/either	Typed success or failure
Task	@oofp/core/task	Lazy asynchronous computation
TaskEither	@oofp/core/task-either	Async computation that can fail
Reader	@oofp/core/reader	Computation that requires context (dependency injection)
ReaderTaskEither	@oofp/core/reader-task-either	DI + async + error handling — the main workhorse
IO	@oofp/core/io	Synchronous side effects
State	@oofp/core/state	Stateful computation

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Composition

Utilities for building data pipelines and composing functions.

Module	Import	Description
pipe	@oofp/core/pipe	Left-to-right value transformation (up to 25 steps)
flow	@oofp/core/flow	Left-to-right function composition (up to 12 steps)
compose	@oofp/core/compose	Right-to-left function composition (up to 26 steps)

import { pipe } from "@oofp/core/pipe";
import { flow } from "@oofp/core/flow";
import { compose } from "@oofp/core/compose";

---

Collections

Functional operations on built-in data structures.

Module	Import	Description
list	@oofp/core/list	Array utilities (reduceRight, grouping, etc.)
object	@oofp/core/object	Object utilities
string	@oofp/core/string	String utilities

---

Utilities

Standalone helpers that complement the core data types.

Module	Import	Description
curry	@oofp/core/curry	Automatic function currying
memo	@oofp/core/memo	Memoization
id	@oofp/core/id	Identity function
promise	@oofp/core/promise	Promise utilities
ref	@oofp/core/ref	Mutable references with lens-based focusing
profunctor	@oofp/core/profunctor	Profunctor for input/output mapping
bi-compose	@oofp/core/bi-compose	Bi-directional composition

---

Transformers

Monad transformers for composing effects.

Module	Import	Description
MaybeT	@oofp/core/maybe-t	Maybe transformer — wraps Maybe inside any monad

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Generic Utilities

Module	Import	Description
utils	@oofp/core/utils	Shared utilities (concurrency, sequence, etc.)

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Type Classes

Abstract interfaces that describe capabilities. See Type Classes & HKT for details.

Module	Import	Description
functor	@oofp/core/functor	Functor, Functor2, Functor3, BiFunctor2
applicative	@oofp/core/applicative	Applicative, Applicative2, Applicative3
monad	@oofp/core/monad	Monad, Monad2, Monad3
chain	@oofp/core/chain	Chain, Chain2, Chain3
join	@oofp/core/join	Joinable, Joinable2, Joinable3
pointed	@oofp/core/pointed	Pointed, Pointed2, Pointed3
delayable	@oofp/core/delayable	Delayable, Delayable2, Delayable3
or-else	@oofp/core/or-else	OrElse2, OrElse3

---

HKT (Higher-Kinded Types)

The encoding system for generic programming over type constructors.

Module	Import	Description
URIS	@oofp/core/URIS	URItoKind<A>, URIS, Kind<F, A> — for 1-parameter types
URIS2	@oofp/core/URIS2	URItoKind2<E, A>, URIS2, Kind2<F, E, A> — for 2-parameter types
URIS3	@oofp/core/URIS3	URItoKind3<R, E, A>, URIS3, Kind3<F, R, E, A> — for 3-parameter types

---

Quick Example

import { pipe } from "@oofp/core/pipe";
import * as RTE from "@oofp/core/reader-task-either";
import * as TE from "@oofp/core/task-either";
import * as E from "@oofp/core/either";

interface AppContext {
  db: { findUser: (id: string) => Promise<User> };
}

const getUser = (id: string): RTE.ReaderTaskEither<AppContext, Error, User> =>
  pipe(
    RTE.ask<AppContext>(),
    RTE.chaint((ctx) =>
      TE.tryCatch(
        () => ctx.db.findUser(id),
        (err) => new Error(`User not found: ${err}`),
      ),
    ),
  );

// Execute at the boundary
const result = await pipe(
  getUser("42"),
  RTE.run({ db: myDbClient }),
)();

pipe(
  result,
  E.fold(
    (err) => console.error(err.message),
    (user) => console.log(user),
  ),
);