aeon-core

The main package of Aeon, a denotationally-designed reactive programming library for TypeScript.

Aeon provides two core abstractions with precise mathematical semantics:

• Event<A, E> — a discrete stream of time-stamped values with a typed error channel
• Behavior<A, E> — a continuous function from time to a value, evaluated lazily when sampled

Features

• Denotational semantics — every combinator has a formal mathematical meaning
• Typed error channel — E = never means a stream provably cannot fail
• V8-optimized — monomorphic sink classes, hidden class discipline, construction-time pipeline fusion
• Three API styles — data-first composition, pipe() with data-last curried operators (P.*), fluent chainable methods
• Behaviors — continuous-time values with generation-based dirty-flag caching, plus numerical integration and differentiation
• Comprehensive — 50+ operators covering transforms, slicing, combining, higher-order, error handling, time, and aggregation
• Small — 1.5 KB gzipped minimal import, 8.3 KB full library

Installation

pnpm add aeon-core aeon-scheduler

Quick Start

import { fromArray, map, filter, observe } from "aeon-core";
import { DefaultScheduler } from "aeon-scheduler";

const scheduler = new DefaultScheduler();

await observe(
  (v) => console.log(v),
  map(
    (x) => x * 2,
    filter((x) => x % 2 === 0, fromArray([1, 2, 3, 4, 5])),
  ),
  scheduler,
);
// 4, 8

Using pipe

import { fromArray, pipe, observe, P } from "aeon-core";
import { DefaultScheduler } from "aeon-scheduler";

const result = pipe(
  fromArray([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]),
  P.filter((x) => x % 2 === 0),
  P.map((x) => x * 2),
  P.take(3),
);

await observe((v) => console.log(v), result, new DefaultScheduler());
// 4, 8, 12

Using the fluent API

import { fromArray, fluent } from "aeon-core";
import { DefaultScheduler } from "aeon-scheduler";

await fluent(fromArray([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]))
  .filter((x) => x % 2 === 0)
  .map((x) => x * 2)
  .take(3)
  .observe((v) => console.log(v), new DefaultScheduler());
// 4, 8, 12

Documentation

• Main README
• Getting Started
• Denotational Semantics
• Optimizations
• Migration from RxJS
• Migration from @most/core

License

MIT