When should I use Static vs Dynamic dispatch?

You should default to Static dispatch (Effectful.Reader.Static). Use Dynamic only when specific MonadReader or MonadState instances are strictly required.

How does this skill handle error propagation?

It enforces placing Error constraints directly on GADT constructors rather than handler signatures, allowing the caller to decide the error scope.

Does it support Template Haskell for effects?

Yes, it recommends using makeEffect for automatic constructor generation but identifies when manual definition is needed for GADTs with effect constraints.

Can I use standard concurrency modules?

No, this skill recommends using Effectful.Concurrent modules instead of Control.Concurrent with liftIO to ensure proper integration with the effect system.

Haskell Effectful Architect

Name: Haskell Effectful Architect
Author: birdgg

bybirdgg

0•

API開発

Standardizes Haskell development using the effectful library with optimized dispatch rules, effect stacks, and error handling patterns.

This skill provides Claude with specialized knowledge of the Haskell effectful ecosystem, enabling it to write high-performance, maintainable effectful code. It enforces specific architectural patterns like consistent effect stack ordering, smart constructor generation using Template Haskell, and proper error propagation through GADT constraints. It is particularly useful for teams migrating from legacy mtl patterns or building robust backend services that require strict control over side effects, concurrency, and testability via pure handlers.

主な機能

01Facilitates seamless migration from MTL to the effectful library

02Automates smart constructor generation with makeEffect and Template Haskell

03Provides specialized patterns for thread-safe concurrency within effects

040 GitHub stars

05Standardizes effect stack ordering to Reader, State, Error, then IOE

06Enforces best practices for error handling and GADT constraints

ユースケース

01Migrating a large Haskell codebase from MTL-style effects to the effectful library

02Designing custom effects for backend services with strict error handling requirements

03Refactoring concurrent IO logic to use effectful-specific concurrency modules

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add birdgg/haskell-claude haskell-effectful

For use in Claude.ai and ChatGPT

Download Skill