API Reference

The library is split into four entry points. Each is independently importable.

Core

import from @nlozgachev/pipelined/core

Type	Description
Maybe	A value that may or may not exist. Replaces T | null | undefined.
Result	An operation that succeeds with a value or fails with an error.
Op	A reusable async operation with typed outcomes and managed execution.
Validation	Like Result, but accumulates all errors instead of stopping at the first.
Task	A lazy, infallible async operation.
TaskResult	A lazy async operation that can fail.
TaskMaybe	A lazy async operation that may return nothing.
TaskValidation	A lazy async operation that accumulates errors.
RemoteData	The four states of a data fetch: NotAsked, Loading, Failure, Success.
Deferred	A minimal async value that always resolves — no rejection handling needed.
These	An inclusive-OR: holds a first value, a second value, or both simultaneously.
Tuple	A typed pair where both values are always present.
Lens	Focus on and immutably update a required nested field.
Optional	Focus on and update an optional nested field or array index.
Reader	Computations that read from a shared environment without threading it everywhere.
State	Thread mutable state through a pipeline without explicit passing.
Logged	A value paired with an accumulated log; thread logs through a pipeline.
Predicate	Composable boolean checks; combine with and, or, not.
Refinement	Type predicates with runtime validation; narrows a broad type to a specific one.
Resource	Safe acquire-use-release lifecycle; guarantees cleanup even when errors occur.
Lazy	Synchronous memoized thunk — runs once, caches the result for subsequent calls.
Equality	Composable equality checks; adapt to fields with by, combine with and.
Ordering	Composable sort comparators; chain with thenBy, flip with reverse, adapt with by.
Combinable	Monoid algebra — fold collections and combine values with a neutral starting point.

Data

import from @nlozgachev/pipelined/data

Module	Description
Arr	Array utilities (find, groupBy, zip, partition) that return Maybe instead of throwing.
Dict	Build, look up, and transform key-value maps.
Num	Number utilities: clamp, range, sum, and arithmetic helpers.
Rec	Record/object utilities: pick, omit, mapValues, and key transformations.
Str	String utilities: trim, split, capitalize, and parsing helpers.
Uniq	Deduplicate and manage sets represented as arrays.

Types

import from @nlozgachev/pipelined/types

Type	Description
Brand	Nominal typing — prevents mixing values that share the same underlying type.
Duration	Represent and manipulate time durations (seconds, milliseconds, etc.).
NonEmptyList	An array guaranteed to have at least one element.

Composition

import from @nlozgachev/pipelined/composition

Function	Description
pipe	Pass a value through a sequence of functions, left to right.
flow	Compose functions into a reusable pipeline.
compose	Compose functions right to left.
tap	Run a side effect without breaking the pipeline.
curry	Convert a multi-argument function into a chain of single-argument functions.
memoize	Cache function results by argument.
identity	Return the argument unchanged.
constant	Return a function that always returns the same value.
not	Negate a predicate function.
once	Call a function at most once; return the cached result thereafter.
uncurry	Convert a curried function to accept a tuple/list of arguments.
flip	Reverse the order of the first two arguments of a function.
converge	Apply a list of unary functions to a value, combining results with a binary/n-ary function.
juxt	Apply multiple functions to the same arguments, returning an array of results.
on	Transform two arguments with a unary function, then apply them to a binary function.