pipeline — tiny TypeScript pipeline builder

A compact, strongly-typed, builder-style pipeline utility for TypeScript. It lets you build a sequence of transformation "passes" that merge fields into a shared environment object. The builder is smart about synchronous vs asynchronous passes — if any pass returns a Promise/thenable at runtime, the final pipeline switches to async behavior.

⚡️ Small, zero-deps, TypeScript-first utility designed for composable transforms.

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Features

• Statically typed pipeline builder with incremental environment merging
• Supports synchronous and asynchronous passes (switches to Promise at runtime)
• Accepts both functions and objects implementing run(env) as passes
• Tiny, well-documented, and easy to drop into TypeScript projects

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Quick example

import { pipeline } from "@codehz/pipeline"; // or relative import

const fn = pipeline<{ input: number }>()
	.addPass((env) => ({ output: env.input + 1 }))
	.addPass((env) => ({ log: `${env.input} => ${env.output}` }))
	.build();

const res = fn({ input: 1 });

// res has inferred type: { input: number; output: number; log: string }
console.log(res);

This will run synchronously and print a merged environment object.

If a pass returns a Promise/thenable at runtime, the returned value from the built pipeline will be a Promise that resolves to the final environment.

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API overview

• pipeline<Input>() — factory that returns a PipelineBuilder instance.
• PipelineBuilder.addPass(fn | { run(env) }) — append a pass. The values returned from the pass are merged into the pipeline's environment and are available to subsequent passes.
• PipelineBuilder.build() — finalize and retrieve the runner function. The runtime result will be synchronous or Promise-based depending on the passes.

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Installation

This repository uses Bun for tests in the included package.json. You can use Bun or any package manager you prefer for installation and running tests.

Using Bun (recommended for local dev here):

bun install

If you prefer npm / yarn:

npm install
# or
yarn install

Note: TypeScript is a peer dependency (this project targets TypeScript v5+).

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Running tests

The repository's tests use Bun’s test runner. Run the tests with:

bun test

If you don't have Bun installed you can still run tests with a different test runner — the codebase uses plain TypeScript/JS and the tests are simple and self-contained.

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Contributing

Contributions are welcome — open an issue or PR for improvements, additional helpers, or new features. Keep changes small and add tests for new behavior.

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License

This project is licensed under the terms in the repository (see LICENSE).