Haskell Weekly

Newsletter

Issue 475 2025-06-05

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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

  • Я ☞ Structural wrapper subtyping by Murat Kasimov

    There are only 5 real types in Я: Void, Unit, Sum, Product and Arrow. That’s it! In this chapter I’m going to describe how to use them, how to wrap/unwrap them and why they are important.

  • Abstracting storage details with Effectful by Frederick Pringle

    How we can use algebraic effects to separate our storage definitions from their implementations.

  • Announcing Ecosystem Partnerships by José Manuel Calderón Trilla

    The Haskell Foundation is pleased to announce a new initiative: Ecosystem Partnerships. These are joint efforts between the Haskell Foundation and service providers with the aim of increasing investment into the wider Haskell ecosystem. These partners sell targeted work on open-source projects important to the Haskell ecosystem, with some of the funds being contributed to the Haskell Foundation for its continued community, infrastructure, and organizing work.

  • Episode 65 – Andy Gordon by The Haskell Interlude

    Andy Gordon from Cogna is interviewed by Sam and Matti. We learn about Andy’s influential work including the origins of the bind symbol in haskell, and the introduction of lambdas in Excel. We go onto discuss his current work at Cogna on using AI to allow non-programmers to write apps using natural language. We delve deeper into the ethics of AI and consider the most likely AI apocalypse.

  • HLS Render Plugin Demo by Joseph Warren

    This is a demo of a Haskell Language Server plugin, which adds customizable type driven actions, that can be run via code lenses.

  • Simple Hindley-Milner in Practice by Andre Van Der Merwe

    In this post, you’ll learn how to build a lightweight Hindley–Milner type checker in Haskell. No advanced theory is required. We’ll apply it to a tiny, LISP-inspired language so you can focus on how inference works.

  • Starting from the End: Solving “Product Except Self” by Monday Morning Haskell

    Today we continue our series exploring LeetCode problems and comparing Haskell and Rust solutions. We’re staying in the realm of list/vector manipulation, but the problems are going to start getting more challenging!

  • The ‘A’ is for ‘Accelerated’: Checking ASCII with SWAR by MLabs

    In particular, we will focus on techniques around data parallelism working over packed data. Using ASCII verification as a test case, we will show not only how such techniques can be used, but how big of an improvement they present over ‘regular’ ways of solving the same problem in Haskell. As part of this, we will discuss various optimizations enabled by such an approach, as well as explain why they work. Lastly, we will see how this could be taken further, and what currently prevents us from doing this (easily) in GHC and Haskell today.

Jobs

  • Haskell Software Developer at Heilmann Software

    We’re looking for a Haskell developer with some previous experience, regardless of whether it was acquired in a traditional professional context. You’re a team player who approaches complex challenges with creativity and pragmatism. It’s important to us that you’re able to think outside the box and understand complex problems holistically.

In brief

Call for participation