JavaScript Function Composition Engine

A powerful, lightweight functional programming engine for JavaScript with:

• pipe() – left‑to‑right composition
• compose() – right‑to‑left composition
• tap() – side‑effect interceptor
• pipeAsync() – async left‑to‑right pipelines
• composeAsync() – async right‑to‑left pipelines
• Pipeline() – chainable FP builder (sync + async)

This project mimics FP engines like Ramda, Lodash FP, and RxJS pipelines while remaining tiny, readable, and production‑ready.

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✨ Features

✔ Function Composition

pipe(f1, f2, f3)(value);
compose(f1, f2, f3)(value);

✔ Tap (Lodash‑style)

pipe(add1, tap(console.log), double)(5);

✔ Full Async Support

await pipeAsync(fetchUser, transform, save)(id);

✔ Chainable API

const result = await Pipeline()
  .pipe(x => x + 1)
  .tap(console.log)
  .pipeAsync(async x => x * 2)
  .runAsync(10);

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📦 Installation

npm install js-composition-engine

(Replace name if you publish with a different package name.)

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📁 File Structure

src/
  index.js
  pipe.js
  compose.js
  tap.js
  pipeAsync.js
  composeAsync.js
  Pipeline.js
  utils/
    validate.js

test/
  *.test.js

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🧠 Usage Examples

Pipe

const { pipe } = require("js-composition-engine");

const add1 = x => x + 1;
const double = x => x * 2;

console.log(pipe(add1, double)(5)); // 12

Compose

compose(f1, f2)(value) // f1(f2(value))

Tap

pipe(
  x => x + 1,
  tap(v => console.log("value:", v)),
  x => x * 3
)(5);

Async Pipeline

await pipeAsync(fetchData, parse, save)(url);

Chainable API

const value = await Pipeline()
  .pipe(x => x + 1)
  .tap(console.log)
  .pipeAsync(async x => x * 2)
  .runAsync(10);

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🧪 Testing

npm test
node playground.js\n
npm run test:coverage
coverage/lcov-report/index.html

Includes full Jest coverage for:

• pipe
• compose
• tap
• async pipelines
• chainable Pipeline API

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🤝 Contributing

PRs welcome.
Feel free to add operators such as:

• map
• filter
• delay
• debounce
• catchError
• retry

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📄 License

MIT

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⭐ Author

Built by an engineer passionate about functional programming and elegant system design.