Polysemy is a high-performance, zero-boilerplate effect system for Haskell, designed to simplify the handling of side effects in functional programs. Unlike traditional monad transformer stacks, Polysemy uses a modern approach based on freer monads and interpreters, allowing developers to define, compose, and interpret effects in a more modular and testable way. It aims to offer both flexibility and performance without sacrificing type safety or expressiveness.

Features

  • Defines effects as pure Haskell data types
  • Enables modular, composable effect handlers
  • Avoids monad transformer boilerplate
  • Supports runtime and compile-time interpreters
  • Promotes testability by mocking effects
  • Designed for high performance and clarity

Project Samples

Polysemy Screenshot 1

Project Activity

See All Activity >

Categories

Libraries

License

BSD License

Follow Polysemy

Polysemy Web Site

Other Useful Business Software
$300 Free Credits to Build on Google Cloud Icon
$300 Free Credits to Build on Google Cloud

New to Google Cloud? Get $300 in credits to explore Compute Engine, BigQuery, Cloud Run, Gemini Enterprise Agent Platform, and more.

Start your next project with $300 in free Google Cloud credit. Spin up VMs, run containers, query petabytes in BigQuery, or build agents with Gemini Enterprise Agent Platform. Once your credits are used, keep building with 20+ always-free tier products including Compute Engine, Cloud Storage, GKE, and Cloud Run functions. No commitment required—just sign up and start building.
Claim $300 Free
Rate This Project
Login To Rate This Project

User Reviews

Be the first to post a review of Polysemy!

Additional Project Details

Programming Language

Haskell

Related Categories

Haskell Libraries

Registered

2025-07-17
Report inappropriate content