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.

Utils

import from @nlozgachev/pipelined/utils

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.
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.