Effect Library Lookup
Quick reference for finding and understanding Effect TypeScript library APIs from the local git subtree at docs/effect/.
When to Use This Skill
Use this skill when:
- Looking up Effect function signatures or implementations
- Finding examples of Effect patterns (Effect.gen, Layer, Context, etc.)
- Understanding how Effect modules work internally
- Checking API availability or deprecation status
- Learning Effect idioms from source code
How to Look Up Effect APIs
1. Use the Effect Docs MCP Server (Fastest)
The effect-docs MCP server provides indexed documentation:
mcp__effect-docs__effect_docs_search: Search for Effect concepts
mcp__effect-docs__get_effect_doc: Get specific documentation by ID
2. Search the Git Subtree Source
For implementation details, search the local source at docs/effect/:
# Find a specific function
grep -r "export const myFunction" docs/effect/packages/effect/src/
# Find usage patterns
grep -rn "Effect.gen" docs/effect/packages/effect/src/
# Find type definitions
grep -rn "interface MyType" docs/effect/packages/effect/src/
3. Read Source Files Directly
Core modules are at: docs/effect/packages/effect/src/<Module>.ts
Example: To understand Effect.map, read docs/effect/packages/effect/src/Effect.ts
Quick Reference
| Task |
Reference |
| Module categories |
references/modules.md |
| Common patterns |
references/patterns.md |
Package Structure
docs/effect/
├── packages/
│ ├── effect/ # Core Effect library
│ │ └── src/ # Source files (Effect.ts, Layer.ts, etc.)
│ ├── platform/ # Cross-platform utilities (HTTP, FileSystem)
│ ├── platform-node/ # Node.js platform implementation
│ ├── platform-browser/ # Browser platform implementation
│ ├── cli/ # CLI building utilities
│ ├── sql/ # SQL database utilities
│ ├── sql-pg/ # PostgreSQL implementation
│ ├── sql-kysely/ # Kysely integration
│ ├── rpc/ # Remote procedure calls
│ ├── cluster/ # Distributed computing
│ ├── opentelemetry/ # OpenTelemetry integration
│ ├── experimental/ # Experimental features
│ └── ai/ # AI integrations (OpenAI, Anthropic, etc.)
Core Modules Quick Lookup
Effect System
| Module |
File |
Purpose |
| Effect |
Effect.ts |
Core effect type and combinators |
| Layer |
Layer.ts |
Dependency injection layers |
| Context |
Context.ts |
Type-safe service context |
| Scope |
Scope.ts |
Resource management |
| Runtime |
Runtime.ts |
Effect execution |
Data Types
| Module |
File |
Purpose |
| Option |
Option.ts |
Optional values |
| Either |
Either.ts |
Success/failure values |
| Chunk |
Chunk.ts |
Immutable arrays |
| HashMap |
HashMap.ts |
Immutable hash maps |
| HashSet |
HashSet.ts |
Immutable hash sets |
| List |
List.ts |
Immutable linked lists |
Concurrency
| Module |
File |
Purpose |
| Fiber |
Fiber.ts |
Lightweight threads |
| Queue |
Queue.ts |
Concurrent queues |
| Ref |
Ref.ts |
Mutable references |
| Semaphore |
Semaphore.ts |
Concurrency limiting |
| PubSub |
PubSub.ts |
Publish/subscribe |
Schema & Validation
| Module |
File |
Purpose |
| Schema |
Schema.ts |
Data validation & encoding |
| ParseResult |
ParseResult.ts |
Parsing results |
| Arbitrary |
Arbitrary.ts |
Property-based testing |
Streaming
| Module |
File |
Purpose |
| Stream |
Stream.ts |
Effectful streams |
| Sink |
Sink.ts |
Stream consumers |
| Channel |
Channel.ts |
Bidirectional streaming |
Scheduling & Time
| Module |
File |
Purpose |
| Schedule |
Schedule.ts |
Retry/repeat schedules |
| Duration |
Duration.ts |
Time durations |
| DateTime |
DateTime.ts |
Date/time handling |
| Clock |
Clock.ts |
Time service |
| Cron |
Cron.ts |
Cron expressions |
Configuration
| Module |
File |
Purpose |
| Config |
Config.ts |
Type-safe configuration |
| ConfigProvider |
ConfigProvider.ts |
Configuration sources |
Common Lookup Patterns
Find Function Signature
# In Effect.ts, functions are well-documented with JSDoc
grep -A 20 "export const map" docs/effect/packages/effect/src/Effect.ts
Find Type Definition
# Look for interface or type alias
grep -n "interface Effect<" docs/effect/packages/effect/src/Effect.ts
Find Examples in Tests
# Tests often have practical examples
grep -rn "Effect.gen" docs/effect/packages/effect/test/
Check Platform APIs
# HTTP client/server
ls docs/effect/packages/platform/src/Http*.ts
# FileSystem
cat docs/effect/packages/platform/src/FileSystem.ts
External References
Tips for Effective Lookups
- Start with MCP search - Use
effect_docs_search for conceptual questions
- Read JSDoc comments - Effect source has excellent inline documentation
- Check tests for examples - Test files show real usage patterns
- Use module tables above - Quickly navigate to the right source file
- Platform packages - HTTP, FileSystem, etc. are in
@effect/platform
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