Effect Monorepo

An ecosystem of tools to build robust applications in TypeScript

Introduction

Welcome to Effect, a powerful TypeScript framework that provides a fully-fledged functional effect system with a rich standard library.

Effect consists of several packages that work together to help build robust TypeScript applications. The core package, effect, serves as the foundation of the framework, offering primitives for managing side effects, ensuring type safety, and supporting concurrency.

Monorepo Structure

The Effect monorepo is organized into multiple packages, each extending the core functionality. Below is an overview of the packages included:

Package	Description
effect	Core package	README
@effect/ai	AI utilities	README
@effect/ai-openai	OpenAI utilities	README
@effect/cli	CLI utilities	README
@effect/cluster	Distributed computing tools	README
@effect/cluster-browser	Cluster utilities for the browser	README
@effect/cluster-node	Cluster utilities for Node.js	README
@effect/cluster-workflow	Workflow management for clusters	README
@effect/experimental	Experimental features and APIs	README
@effect/opentelemetry	OpenTelemetry integration	README
@effect/platform	Cross-platform runtime utilities	README
@effect/platform-browser	Platform utilities for the browser	README
@effect/platform-bun	Platform utilities for Bun	README
@effect/platform-node	Platform utilities for Node.js	README
@effect/platform-node-shared	Shared utilities for Node.js	README
@effect/printer	General-purpose printing utilities	README
@effect/printer-ansi	ANSI-compatible printing utilities	README
@effect/rpc	Remote procedure call (RPC) utilities	README
@effect/rpc-http	HTTP-based RPC utilities	README
@effect/sql	SQL database utilities	README
@effect/sql-clickhouse	An @effect/sql implementation for ClickHouse.	README
@effect/sql-d1	An @effect/sql implementation for Cloudflare D1.	README
@effect/sql-drizzle	An @effect/sql implementation for Drizzle.	README
@effect/sql-kysely	An @effect/sql implementation for Kysely.	README
@effect/sql-libsql	An @effect/sql implementation using the @libsql/client library.	README
@effect/sql-mssql	An @effect/sql implementation using the mssql tedious library.	README
@effect/sql-mysql2	An @effect/sql implementation using the mysql2 library.	README
@effect/sql-pg	An @effect/sql implementation using the postgres.js library.	README
@effect/sql-sqlite-bun	An @effect/sql implementation using the bun:sqlite library.	README
@effect/sql-sqlite-do	An @effect/sql implementation for Cloudflare Durable Objects sqlite storage.	README
@effect/sql-sqlite-node	An @effect/sql implementation using the better-sqlite3 library.	README
@effect/sql-sqlite-react-native	An @effect/sql implementation using the react-native-quick-sqlite library.	README
@effect/sql-sqlite-wasm	An @effect/sql implementation using the @sqlite.org/sqlite-wasm library.	README
@effect/typeclass	Functional programming type classes	README
@effect/vitest	Testing utilities for Vitest	README

Documentation

Website

For detailed information and usage examples, visit the Effect website.

API Reference

For a complete API reference of the core package effect, see the Effect API documentation.

Introduction to Effect

Get started with Effect by watching our introductory video on YouTube. This video provides an overview of Effect and its key features:

Connect with Our Community

Join the Effect community on Discord to connect with other developers, ask questions, and share insights: Join Effect's Discord Community.

Contributing via Pull Requests

We welcome contributions via pull requests! Here are some guidelines to help you get started:

Setting Up Your Environment

Begin by forking the repository and clone it to your local machine.

Navigate into the cloned repository and create a new branch for your changes:

git checkout -b my-branch

Ensure all required dependencies are installed by running:

pnpm install  # Requires pnpm version 9.0.4

Making Changes

Implement Your Changes

Make the changes you propose to the codebase. If your changes impact functionality, please add corresponding tests to validate your updates.

Validate Your Changes

Run the following commands to ensure your changes do not introduce any issues:

• pnpm codegen (optional): Re-generate the package entrypoints in case you have changed the structure of a package or introduced a new module.
• pnpm check: Confirm that the code compiles without errors.
• pnpm test: Execute all unit tests to ensure your changes haven't broken existing functionality.
• pnpm circular: Check for any circular dependencies in imports.
• pnpm lint: Ensure the code adheres to our coding standards.
  • If you encounter style issues, use pnpm lint-fix to automatically correct some of these.
• pnpm dtslint: Run type-level tests.
• pnpm docgen: Ensure the documentation generates correctly and reflects any changes made.

Document Your Changes

JSDoc Comments

When adding a new feature, it's important to document your code using JSDoc comments. This helps other developers understand the purpose and usage of your changes. Include at least the following in your JSDoc comments:

• A Short Description: Summarize the purpose and functionality of the feature.
• Example: Provide a usage example under the @example tag to demonstrate how to use the feature.
• Since Version: Use the @since tag to indicate the version in which the feature was introduced. If you're unsure about the version, please consult with a project maintainer.
• Category (Optional): You can categorize the feature with the @category tag to help organize the documentation. If you're unsure about what category to assign, ask a project maintainer.

Note: A HTML utility file, code2jsdoc-example.html, has been added to assist with creating JSDoc @example comments. This web-based interface includes two text areas:

1. An input textarea for pasting example code.
2. An output textarea that dynamically generates formatted JSDoc @example comments.

This utility helps ensure consistent formatting and streamlines the process of documenting examples. See the following example of its usage:

Example Input:

import { Effect } from "effect"

console.log(Effect.runSyncExit(Effect.succeed(1)))
/*
Output:
{
  _id: "Exit",
  _tag: "Success",
  value: 1
}
*/

Output:

*
* @example
* ```ts
* import { Effect } from "effect"
*
* console.log(Effect.runSyncExit(Effect.succeed(1)))
* // Output:
* // {
* //   _id: "Exit",
* //   _tag: "Success",
* //   value: 1
* // }
* ```
*

By using this utility, you can save time and maintain consistency in your JSDoc comments, especially for complex examples.

Changeset Documentation

Before committing your changes, document them with a changeset. This process helps in tracking modifications and effectively communicating them to the project team and users:

pnpm changeset

During the changeset creation process, you will be prompted to select the appropriate level for your changes:

• patch: Opt for this if you are making small fixes or minor changes that do not affect the library's overall functionality.
• minor: Choose this for new features that enhance functionality but do not disrupt existing features.
• major: Select this for any changes that result in backward-incompatible modifications to the library.

Finalizing Your Contribution

Commit Your Changes

Once you have documented your changes with a changeset, it’s time to commit them to the repository. Use a clear and descriptive commit message, which could be the same message you used in your changeset:

git commit -am 'Add some feature'

Linking to Issues

If your commit addresses an open issue, reference the issue number directly in your commit message. This helps to link your contribution clearly to specific tasks or bug reports. Additionally, if your commit resolves the issue, you can indicate this by adding a phrase like ", closes #<issue-number>". For example:

git commit -am 'Add some feature, closes #123'

This practice not only helps in tracking the progress of issues but also automatically closes the issue when the commit is merged, streamlining project management.

Push to Your Fork

Push the changes up to your GitHub fork:

git push origin my-branch

Create a Pull Request

Open a pull request against the appropriate branch on the original repository:

• main branch: For minor patches or bug fixes.
• next-minor branch: For new features that are non-breaking.
• next-major branch: For changes that introduce breaking modifications.

Please be patient! We will do our best to review your pull request as soon as possible.