Ecosystem Overview

Effect is a monorepo with the effect package at its core and a set of driver packages for specific platforms and databases.

Core Packages

Package	Purpose
`effect`	Core framework: Effect type, Context, Layer, Fiber, Stream, Schedule, Scope, Schema, and all `unstable/*` namespaces
`@effect/vitest`	Vitest integration with `it.effect`, layer test helpers
`@effect/opentelemetry`	OpenTelemetry SDK integration for existing OTel setups
`@effect/sql-*`	SQL drivers: `sql-pg`, `sql-mysql2`, `sql-sqlite-node`, `sql-libsql`, `sql-d1`, `sql-mssql`, `sql-clickhouse`
`@effect/platform-node`	Node.js-specific runtime services (NodeRuntime)
`@effect/platform-bun`	Bun-specific runtime services (BunRuntime)
`@effect/platform-browser`	Browser-specific runtime services

Gotcha: In v4, @effect/platform, @effect/cli, @effect/rpc, @effect/cluster, @effect/workflow, @effect/ai, and @effect/sql were merged into effect/unstable/*. You no longer install these as separate packages. Only the driver packages (@effect/sql-pg, etc.) and platform runtime packages remain external.

v4 Unstable Namespaces

Everything that was a separate package in v3 now lives under effect/unstable/*:

Namespace	What’s There	v3 Package
`http`	HTTP client, server, router, middleware, body parsing, multipart	`@effect/platform`
`httpapi`	Schema-first HTTP API builder, OpenAPI, Swagger, Scalar	`@effect/platform`
`rpc`	Type-safe RPC, client/server, workers	`@effect/rpc`
`cluster`	Distributed entities, sharding, runners, singletons	`@effect/cluster`
`workflow`	Durable workflows, activities, durable queues	`@effect/workflow`
`cli`	Command-line apps, flags, prompts, help docs	`@effect/cli`
`ai`	Language models, chat sessions, tools, tokenizers, MCP	`@effect/ai`
`sql`	SQL clients, migrations, resolvers, schema, streams, models	`@effect/sql`
`reactivity`	Reactive state, atoms, async results, hydration	`@effect/experimental`
`observability`	OTLP exporters (tracer, metrics, logger)	`@effect/opentelemetry`
`persistence`	Key-value stores, persisted caches, rate limiters	`@effect/experimental`
`encoding`	MsgPack, NDJSON, SSE	`@effect/platform` / `@effect/experimental`
`workers`	Worker threads, transferable objects	`@effect/platform`
`process`	Child processes, spawner	`@effect/platform`
`devtools`	DevTools server, client, schema	`@effect/experimental`
`eventlog`	Event journals, event groups	`@effect/experimental`
`socket`	Socket client and server	`@effect/platform`
`schema`	Model, variant schema	`@effect/sql` / `@effect/experimental`

The unstable prefix means these APIs may change between minor versions. The core effect module (Effect, Context, Layer, Stream, Schema, Schedule, Scope, Fiber, etc.) is stable.

What’s Stable in Core

These modules ship in the effect package root and are API-stable:

Effect - core effect type and combinators
Context - dependency injection
Layer - resource lifecycle and composition
Fiber - lightweight virtual threads
Stream - pull-based effectful sequences
Schedule - retry and repeat policies
Scope - resource lifecycle management
Schema - data validation and domain modeling
Channel - streaming pipelines
PubSub / Queue - concurrent messaging
Ref / Deferred - mutable references and promises
DateTime / Duration / Clock - time abstractions
Metric / Logger / Tracer - observability
HashMap / HashSet / Chunk / Trie - data structures
Array / String / Number / Record - standard library
Predicate / Equal / Hash - equality and type guards

Effect LSP (tsgo)

Effect maintains a fork of the TypeScript compiler called tsgo that provides faster type checking and better error messages for Effect code. It’s a drop-in replacement for tsc:

npx @effect/tsgo check

Tip: tsgo is significantly faster than stock TypeScript for large Effect codebases. Use it in CI for faster feedback loops.

VS Code Extension

The Effect VS Code extension provides:

Inline type signatures for Effect types
Quick fixes for common patterns (missing yield*, wrong return)
Documentation on hover for Effect APIs
Better error message rendering

Effect Playground

The Effect Playground is an in-browser editor for experimenting with Effect code. Useful for trying snippets without setting up a project.

Linting Rules

Effect provides ESLint rules that catch common mistakes:

yield* without return for terminal effects
try-catch inside generators
Using .pipe with Effect.fn

Community

Resource	Where
Discord	discord.gg/effect-ts - main community hub
Effect Days	Annual conference, talks on Effect patterns and ecosystem
Effect Podcast	Interviews with Effect users and core team members
Workshops	Periodic online workshops on Effect fundamentals and advanced patterns
GitHub	Effect-TS/effect - source and issues
Website	effect.website - docs and API reference