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 dancing space leak by Tom Sydney Kerckhove

  This is the story of a space leak in the Social Dance Today server and how we fixed it.

• Deriving Simple Recursive Functions by Jack Kelly

  I used to teach Haskell to first-year university students, and many of them struggled to write their first recursive functions.

• Haskell at work by Marco Perone

  In this post I’d like to summarise what Tweag is doing in this space. In particular, there are three projects we are working on to help make Haskell adoption and usage a little bit simpler and more straightforward.

• Linking Smaller Haskell Binaries by Brandon Simmons

  Haskell binaries can get quite large (think ~100MB), especially for projects with many transitive dependencies. Here are two strategies that can help at link time, the latter being more experimental.

• New Hackage Server Features

  Updating to announce a whole bunch of new features in the latest redeploy, with a few yet to come.

• One Step Beyond by Jean-Hugues de Raigniac

  The problem is not “should I use an effect library?” but “how do I compare the pros and cons of these libraries to find the one fitting my project and my team skills?”

• Parallel streaming in Haskell: Part 2 - Optimized parallel aggregations by Channable

  This is part 2 in our series about the parallel streaming evaluator that we use at Channable, where we use Haskell with the Conduit library to produce both result values and parallel work units in a single stream.

• Property-based testing stateful systems: a tutorial by Stevan Andjelkovic

  Given this it’s perhaps a bit surprising that there are relatively few resources about applying PBT to stateful systems. This repository is an attempt to close that gap and try to make PBT stateful systems more common.

Jobs

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• Haskell Engineer at Artificial

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In brief

• Chat GPT and Functional Programming by Monday Morning Haskell

  Last week I explored what Chat GPT has to say about monads. But it’s interesting to go beyond this single area and see what its thoughts are about functional programming (FP) in general, and how different languages fit within this paradigm.

• Don’t edit dependency bounds manually, with this CI setup by Joachim Breitner

  The last point made me write a new tool, cabal-plan-bounds, that takes multiple of Cabal build plans (plan.json), and changes the dependency version ranges in the .cabal file to reflect the versions that are actually used on CI.

• GHC+DH Weekly Update #3, 2023-01-11 by Vladislav Zavialov

  This week I continued to work on @k-binders in type declarations, and I focused on two issues in particular: associated types and kind inference.

• GHC WebAssembly Weekly Update, 2023-01-11 by Cheng Shao

• Haskell Foundation DevOps Weekly Update, 2023-01-11 by Bryan Richter

  I just got back from the first Helsinki Haskell Meetup that has been held in over three years, which pleases me as an excuse for my tardiness!

• Scrap your boilerplate, with recursive continuations

  The core trick I want to introduce is simple: Adding some knot-tying to continuations lets us add a recurse operator which is really useful when writing generic traversals.

Show & tell

• Copilot version 3.13 by Ivan Perez

  Copilot is a stream-based DSL for writing and monitoring embedded C programs, with an emphasis on correctness and hard realtime requirements.

• ldtk-types by Sandy Maguire

  I decided I wanted to use the fantastic LDtk editor to design levels for my entry, but was horrified to see that there didn’t already exist bindings.

• monadic-bang by Jakob Brünker

  A plugin for GHC which takes expressions prefixed with a ! and effectively takes them out of their monadic context, by creating bind statements in the do-block surrounding the expression.

Call for participation

• pandoc: HTML → texinfo: <var> within <code> not taken into account
• wasp: examples/Waspello: Text protrudes out of the card when too long to fit