Haskell Weekly

Newsletter

Issue 532 2026-07-09

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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

  • Applicatives (aka Squishables) by Tea Leaves

    Today we dip into Set 15 of the MOOC from haskell.mooc.fi. Along the way we provide the new, better name for Applicatives: “Squishables”.

  • Data-directed programming in Haskell (SICP 2.4.3) by kqr

    Last week, we looked at tagged data in Haskell. The authors of sicp weren’t convinced that’s the best approach, so they move on to data-directed programming. We’ll do the same.

  • Extreme Haskell: Typed Expression EDSLs (Part 1) by Justin Le

    I always say, inside every Haskeller there are two wolves, living on opposite ends of the Haskell Fancy Code Spectrum. Are you going to write “simple Haskell”, using basic GHC 2010 tools and writing universal Haskell that every introductory course offers, trying to keep the code as immediately understandable and accessible? Or are you going to pile in all of the Haskell type system and evaluation tricks you can find and turn on all the extensions, and go full fancy?

  • Mechanized type inference for record concatenation by Gabriella Gonzalez

    The context behind this post is that I’m working on a type checker and language server for Nix and there are three features of the language which make it tricky to typecheck (which I’ll dub the “three horsemen of Nix type inference”).

  • Tagged data in Haskell (SICP 2.4.2) by kqr

    I have a copy of sicp, or as it is also known, The Wizard Book. This book is widely praised, but I can’t take the time to work my way through all of it. However, sometimes I jump into parts of it that look interesting. Today, we’ll see how to support multiple representations of data through tagging. This article is written in Haskell throughout, but at the start it will look a lot like the Lisp code in sicp. I have intentionally tried to recreate the sicp solution as closely as possible, including dynamic typing and all. See the appendix if you’re curious how it works.

  • Teo Camarasu - Optimising for fast builds with GHC by The Haskell Foundation

    From Haskell Ecosystem Workshop 2026.

  • ZuriHac 2026 Video Playlist by Farhad Mehta

    It was great to see you at ZuriHac 2026. In case you couldn’t attend, or would like to relive the magic, the following playlist will contain recordings from the event. We plan to process and release one or more videos every Friday, starting 10.07.2026 until around 18.09.2026, so bookmark the above playlist to find something new every weekend over the summer!

Jobs

  • Senior/Staff Haskell Developer - Remote from EU/EEA by matsumonkie

    Scrive still needs pragmatic, production-oriented Haskell developers. We do a bit of “non-boring Haskell” (type-level techniques, effect systems - Effectful, which we actively contribute to) and maintain a few other OSS projects, but primarily we build stuff that serves our customers, even if it means going beyond “pure”. The product is in the e-signing space, so if you think or know you like legaltech, we are the company you want to join.

In brief

Show & tell

Call for participation