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

• Benchmarking Haskell LLM proficiency with AOC puzzles by Benjamin Thomas

  I’ve been wondering how I could evaluate different models myself, and not rely on advertised benchmarks, which could be more or less optimized for marketing purposes. I’ve summarized in a blog post my strategy for doing so, and I feel pretty good about it for now.

• Episode 77 – Franz Thoma by The Haskell Interlude

  Franz Thoma is Principal Consultant at TNG Technology Consulting, and an organizer of MuniHac. Franz sees functional programming and Haskell as a tool for thinking about software, even if the project is not written in Haskell. We had a far-reaching conversation about the differences between functional and object-oriented programming and their languages, software architecture, and Haskell adoption in industry.

• Ghc-debug-web - Web visualiser for ghc-debug by GBZ

  ghc-debug-web is like ghc-debug-brick but on the web, with graphic visualisations of the heap. Like ghc-debug-brick, you can instrument a debuggee with GHC.Debug.Stub, and then look at the memory layout.

• Haskell for Elm developers: giving names to stuff (Part 6 - Foldable) by Flavio Corpa

  In my last post, we talked about Semigroups and Monoids, and we even discovered the deep relationship between folds and Monoids. But we left something out: the Foldable typeclass itself! So today, let’s give it the attention it deserves.

• Making Haskell Talk to PostgreSQL Without Suffering by Ian Duncan

  How to eliminate the three performance taxes that make database queries slow: encoding overhead, round-trip latency, and N+1 query patterns.

• Template Haskell: From AST to DSL by Arthi-chaud

  So with a bit of code generation, I came up with template-haskell-natural, a DSL that allows building TH ASTs through monadic operations. The library is named that way because writing the meta-program feels natural.

In brief

• Announcement: Esqueleto postgis v4 by Jappie J. T. Klooster

  I was recently tasked again with figuring out where stuff is in space. I decided this was an opportunity to cleanup the esqueleto postgis library and releasing v4!

• cassava 0.5.5.0 by Michael Chavinda

• Haskell.org accepted for Google Summer of Code 2026 by Aaron Allen

  We’re very excited to announce that Haskell.Org has been accepted into the Google Summer of Code 2026 program. We hope that, like last year, it will lead to a whole range of improvements to the Haskell ecosystem, and to new faces joining our community!

• kdl-hs 1.0.0 released with v2 support by Brandon Chinn

  kdl-hs is a parser for the KDL configuration language, providing both monadic and arrow-based decoding functionality. v1.0.0 reimplements the parser to be v2 compliant.

• New Haskell Debugger Release: v0.12 by Rodrigo Mesquita

  I’m happy to announce a new release of the new modern step-through interactive debugger.

• sabela - A reactive Notebook for Haskell by Michael Chavinda

  The project has two purposes. Firstly, it is an attempt to design and create a modern Haskell notebook where reactivity is a first class concern. Secondly, it is an experiment ground for package/environment management in Haskell notebooks (a significant pain point in IHaskell).

• Stack 3.9.3 by Mike Pilgrem

• Updated iced-hs to iced 0.14 by reki

  iced-hs is a Haskell wrapper for iced Rust library. It provides an Elm-like way to build desktop apps.

Show & tell

• Functors represented by objects by Murat Kasimov

  I’ve been working recently on functors that can be represented by objects - it was the missing piece of the puzzle that makes Я powerful enough to not use a class of custom functions! You can use this concept to initialise data structures, evaluate functions/stateful computations, do some scope manipulation. Other cases yet to be explored, but I’m pretty happy with the intermediate results.

Call for participation

• beam: Add support for COPY statement