ts-iterable-functions

Type-safe, LINQ-inspired iterable utilities for TypeScript and JavaScript, built for fluent composition and modern functional pipelines.

Highlights

• Composable by default – every operator ships in source-first and pipe-first forms so you can pivot between array-style calls and unary pipelines without adapters.
• Zero-dependency core – tiny footprint with native ESM and CJS bundles generated by esbuild for fast installs and rapid builds.
• End-to-end type safety – aggressive generics keep key selectors, reducers, and joins fully inferred across long pipelines.
• Drop-in LINQ ergonomics – familiar primitives like map, groupBy, orderBy, and zip behave the way seasoned C# and F# developers expect.
• Pipe-friendly ecosystem – pairs naturally with ts-functional-pipe and other unary-first composition helpers.

Quick start

Install

npm install ts-iterable-functions ts-functional-pipe ts-equality-comparer ts-comparer-builder

Compose a strongly typed pipeline

import { pipeInto } from "ts-functional-pipe";
import { map, orderBy, thenBy, toArray } from "ts-iterable-functions";

const cars = [
  { manufacturer: "Ford", model: "Escort" },
  { manufacturer: "Ford", model: "Cortina" },
  { manufacturer: "Renault", model: "Clio" },
  { manufacturer: "Vauxhall", model: "Corsa" },
  { manufacturer: "Ford", model: "Fiesta" },
  { manufacturer: "Fiat", model: "500" },
];

const orderedCars = pipeInto(
  cars,
  orderBy((c) => c.manufacturer),
  thenBy((c) => c.model),
  toArray()
);

console.log(orderedCars);
// → deterministically ordered list with full type inference at every hop

Works great for

• Data transformation pipelines in backends or frontends
• Analytics dashboards and reporting utilities
• Lightweight ETL tasks without pulling in stream frameworks
• Crafting reusable collection helpers for design systems and SDKs
• Replacing brittle nested loops with readable, testable pipelines

Pipe-first or source-first—your call

Every transformer is available as _operator(source, ...args) and operator(...args)(source).

import { _map, map, toArray } from "ts-iterable-functions";
import { pipeInto } from "ts-functional-pipe";

const numbers = [1, 2, 3];

const doubledLegacy = _map(numbers, (value) => value * 2);
const doubledPipeline = pipeInto(numbers, map((value) => value * 2), toArray());

Switching between forms keeps refactors painless while preserving full generic inference.

Core building blocks

• Generators – range, repeat, repeatGenerate, fromSingleValue
• Transformers – aggregate, concat, distinctBy, groupBy, intersect, orderBy, selectMany, union, zip, and dozens more
• Aggregations – average, count, maxBy, minBy, sum
• Materializers – toArray, toLookup, toMap, toSet

Browse the full API reference in the online docs for detailed signatures and examples.

Plays nicely with ts-functional-pipe

• Leverages pipe, pipeInto, and compose while preserving discriminated unions and narrowed types
• Ships lightweight helpers like indexed, groupAdjacent, and fullOuterJoin that plug directly into unary pipelines

Learn more

• Read the full documentation: biggyspender.github.io/ts-iterable-functions
• Explore class definitions and helpers: Docs hierarchy
• Generated API listings for every operator: Docs functions/_map

Heads up: versions 5.x and later are bundled with esbuild and drop IE11 support.

🤝 Contributing and community

We welcome issues, feature ideas, and pull requests. Start a conversation in issues or discussions, and check CONTRIBUTING.md before raising a PR.