Haskell Weekly

Welcome to another issue of Haskell Weekly! Haskell is a safe, purely functional programming language with a fast, concurrent runtime. This is a weekly summary of what’s going on in its community.

Featured

• A Fast Bytecode VM for Arithmetic: The Compiler by Abhinav Sarkar

  In this post, we write the compiler for our AST to bytecode, and a decompiler for the bytecode.

• Decidable equality for indexed data types, take 2 by Brent Yorgey

  In a post from a year ago, I explored how to prove decidable equality in Agda of a particular indexed data type. Recently, I discovered a different way to accomplish the same thing, without resorting to embedded sigma types.

• Episode 69 – Jurriaan Hage by The Haskell Interlude

  Today’s guest is Jurriaan Hage. Jurriaan is a professor at Heriot-Watt University in Edinburgh who’s worked with and on Haskell for many years. He’s known for the Helium Haskell compiler, specifically designed for teaching, and he has plenty of other projects related to Haskell, including improvements to the type system, the generation of better error messages, or detection of plagiarism.

• Episode 9 - Hécate by Func Prog Podcast

  Hécate is a Haskell engineer and prolific contributor to the Haskell ecosystem—in this episode we talk about using Haskell in production, effect systems and how empathy can help you build better software.

• The Baby Paradox in Haskell by Justin Le

  First, some background: when using Haskell as a theorem prover, you represent the theorem as a type, and proving it involves constructing a value of that type — you create an inhabitant of that type.

Jobs

• Postdoc positions on foundations of type classes and type families at the University of Iowa, starting October 2025 by J. Garrett Morris

  I am seeking applications for a postdoctoral scholar at the University of Iowa, starting in October of 2025. We study extensibility and modularity in high-level typed functional programming languages, particularly Haskell. The post-doctoral scholar will contribute to an NSF-funded project exploring a new semantic foundation for type classes and type families in Haskell. Their work may include formalizing the new approach in Lean 4, implementing it in GHC, and evaluating that implementation.

In brief

• Haskell bindings for Tabler Icons by Sridhar Ratnakumar

  I’d like to announce a new Haskell library called tabler-icons which provides simple bindings for 5000+ icons from Tabler Icons.

• Rel8-1.7.0 released by Teo Camarasu

  We’re happy to announce the release of Rel8 1.7 ! Rel8 is a Haskell library for interacting with PostgreSQL databases, built on top of the fantastic Opaleye library.

Show & tell

• Sets & Heaps in Haskell and Rust by Monday Morning Haskell

  Today, we’ll solve a problem that relies on using the “set” data structure as well as the “heap” data structure.

Call for participation

• swarm: Redraw the screen when a structure is recognized
• text-show: Test suite failures misreport source locations