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

• Adding Operational Transformation To Butler by Tristan de Cacqueray

  Butler is a web-based multiplayer virtual operating system that features collaborative applications. This post shows how I integrated Operational Transformation (OT) to enable users to simultaneously edit a text document in Butler.

• Where does the name “algebraic data type” come from? by Lysxia

  “Algebraic data types” is a beloved feature of programming languages with such a mysterious name. Where does this name come from?

• Analyzing Haskell stability by Jappie Klooster

  Recently, we’ve been curious about what Haskell ecosystem and GHC changes cause the most breakage. A suggestion was made to do a quantitative analysis of “head.hackage”. “head.hackage” is a repository of patches for Hackage. GHC engineers use these to test out new GHC builds on a wide range of Hackage packages without having to upstream a patch, which can take time.

• Announcing autodocodec-nix and Nix integration for opt-env-conf by Tom Sydney Kerckhove

  This post announces autodocodec-nix, a new companion library for autodocodec that lets you generate a NixOS module options from any Codec.

• Data.Maybe, and thoughts on library design by Srijan Paul

  Earlier today, I was reading a paper about monoids that briefly highlighted an interesting flaw in older versions of Haskell’s standard library. The problem—although fixed later—still serves as an interesting case study for library design. So I took a break from the study session to log my thoughts here before I forget.

• Functional programming languages should be so much better at mutation than they are by Prophet

  Functional languages need to allow mutation in some way if they don’t want nearly every program to suffer from completely unnecessary overhead in terms of both time and implementation complexity. Existing languages have a few options here but I don’t think any of these are good enough.

• Haskell Nuggets: k-means by Justin Le

  AI is hot, so let’s talk about some “classical machine learning” in Haskell with k-means clustering! Let’s throw in some dependent types too.

• The Haskell Unfolder Episode 30: runST by Andres Löh, Edsko de Vries

  In Haskell, the ST type offers a restricted subset of the IO functionality: it provides mutable variables, but nothing else. The advantage is that we can use mutable storage locally, because unlike IO, ST allows us to escape from its realm via the function runST. However, runST has a so-called rank-2 type. In this episode, we will discuss why this seemingly complicated type is necessary to preserve the safety of the operation.

Jobs

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In brief

• emoji-board: Blazing fast emoji picker for linux / wayland written in Haskell by Luca Leon Happel

• htmx-0.0.0.1 a library for using HTMX in haskell by Jonathan Lorimer

• Stack 3.1.1 by Mike Pilgrem

• streamly-0.10 with fast binary serialization by Harendra Kumar

Show & tell

• Typed-fsm examples: ATM and todoList by Miao Yang

Call for participation

• htmx: Extend hxSwapS_ by adding support for modifiers
• NeoHaskell: Setup GitHub Actions cache