Free monads from scratch - A way to deal with effectful programs

Free monads from scratch is a talk about Free monads, their motivation, their use cases for "real-world applications", and their implementation. It is mostly based on Wouter Swierstra's paper, Data Types à la carte.

Disclaimer

The implementations in this repository are solely meant for educational purposes. They are neither stack-safe nor very performant, and shouldn't be used in production. If you want the awesomeness of Free monads for your application, please use one of the widely-available implementations.

Repository structure

• presentation.md is the source for the slideshow, generated using Deckset
• scala-samples is a sbt project with several modules:
  • The data-types-a-la-carte module contains a Free monad implementation loosely based on Data types à la carte
  • The cats-free-monads module contains examples of using cats-free to structure programs
• Similarly, haskell-samples is a stack project with several packages
  • The data-types-a-la-carte package contains a Free monad implementation loosely based on Data types à la carte
  • The free-package package contains examples of using free to structure programs

Acknowledgments

This talk wouldn't have been possible without the work of these amazing people:

• Cats contributors for their work on the cats-free module, among everything else.
• James Haydon with his article Free monads for cheap interpreters
• Edward A. Kmett and contributors for the free Haskell package
• Adam Rosien with his article, What is an effect which provides an excellent introduction to effects, and a nice motivation for Free monads
• Wouter Swierstra with his paper, Data types à la carte which provides the reference implementation for Free monads, on which this presentation's code is mostly based.

Get in touch

• E-mail: hey [at] guillaumebogard [dot] dev
• Homepage: guillaumebogard.dev
• Twitter: @bogardguillaume