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

Project Activity

See All Activity >

Categories

Libraries

License

BSD License

Follow Polysemy

Polysemy Web Site

Other Useful Business Software
Forever Free Full-Stack Observability | Grafana Cloud Icon
Forever Free Full-Stack Observability | Grafana Cloud

Our generous forever free tier includes the full platform, including the AI Assistant, for 3 users with 10k metrics, 50GB logs, and 50GB traces.

Built on open standards like Prometheus and OpenTelemetry, Grafana Cloud includes Kubernetes Monitoring, Application Observability, Incident Response, plus the AI-powered Grafana Assistant. Get started with our generous free tier today.
Create free account
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