Effect-TS Expert

Expert guidance for functional programming with the Effect library, covering error handling, dependency injection, composability, and testing patterns.

Prerequisites Check

Before starting any Effect-related work, verify the Effect-TS source code exists at ~/.effect.

If missing, stop immediately and inform the user. Clone it before proceeding:

git clone https://github.com/Effect-TS/effect.git ~/.effect

Research Strategy

Effect-TS has many ways to accomplish the same task. Proactively research best practices using the Task tool to spawn research agents when working with Effect patterns, especially for moderate to high complexity tasks.

Research Sources (Priority Order)

1. Codebase Patterns First — Examine similar patterns in the current project before implementing. If Effect patterns exist in the codebase, follow them for consistency. If no patterns exist, skip this step.

2. Effect Source Code — For complex type errors, unclear behavior, or implementation details, examine the Effect source at ~/.effect/packages/effect/src/. This contains the core Effect logic and modules.

When to Research

HIGH Priority (Always Research):

• Implementing Services, Layers, or complex dependency injection
• Error handling with multiple error types or complex error hierarchies
• Stream-based operations and reactive patterns
• Resource management with scoped effects and cleanup
• Concurrent/parallel operations and performance-critical code
• Testing patterns, especially unfamiliar test scenarios

MEDIUM Priority (Research if Complex):

• Refactoring imperative code (try-catch, promises) to Effect patterns
• Adding new service dependencies or restructuring service layers
• Custom error types or extending existing error hierarchies
• Integrations with external systems (databases, APIs, third-party services)

Research Approach

• Spawn multiple concurrent Task agents when investigating multiple related ...