Algebraic Effects from Scratch by Kit Langton

April 10, 2024

Kit Langton explores algebraic effects, emphasizing separating syntax from semantics. Kit demonstrates this through the Kyo library, discussing syntax and semantics using method examples. He showcases handling failures and non-determinism, refactors code for efficiency, and introduces concepts like “and-then,” “flatMap,” and “map.” The goal is to create a simple console DSL with type inference and sequential composition, enabling building larger programs as a single syntax tree. Kit also discusses challenges like type inference issues and making effects extensible and composable, promoting the Kyo library’s speed and modular design for better optimization and JVM compatibility.

Algebraic Effects from Scratch: A comprehensive overview

Algebraic Effects from Scratch is a presentation by Kit Langton, delivered at the Func Prog Sweden MeetUp. In this comprehensive overview, we delve into Kit’s demonstration of building a simple console DSL (Domain Specific Language) using algebraic effects and extending it with sequential composition and arbitrary effects.


Introduction to algebraic effects

Kit Langton begins by introducing the concept of algebraic effects, a powerful programming paradigm that enables expressive and modular code. He discusses the benefits of algebraic effects, such as improved composability and code readability. Kit emphasizes the importance of understanding the underlying principles of algebraic effects to harness their full potential.


Building a simple console DSL

Kit demonstrates how to build a simple console DSL step by step, highlighting key concepts such as syntax tree construction and interpreter handling. Through practical examples, he illustrates how algebraic effects can be leveraged to create elegant and efficient code.


Extending the DSL with sequential composition and arbitrary effects

Kit expands upon the console DSL by adding sequential composition and arbitrary effects. He explains how to extend the DSL to support additional operations, such as reading the current time or accessing environment variables. Kit introduces the concept of Handlers, which enable the embedding of arbitrary effects into the DSL. Through live coding examples, he demonstrates the flexibility and modularity of algebraic effects in action.


Conclusion: Unlocking the power of algebraic effects

Algebraic Effects from Scratch provides a comprehensive overview of algebraic effects and their application in modern programming. Kit Langton’s insightful presentation offers a deep dive into the principles and practicalities of building DSLs with algebraic effects. By mastering these concepts, developers can unlock new levels of expressiveness and flexibility in their code, paving the way for more robust and maintainable software solutions.


Additional resources

Check out more from the MeetUp Func Prog Sweden. Func Prog Sweden is the community for anyone interested in functional programming. At the MeetUps the community explore different functional languages like Erlang, Elixir, Haskell, Scala, Clojure, OCaml, F# and more.