Haskell Weekly


Issue 364 2023-04-20

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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.


  • GHC 9.4.5 is now available by Zubin Duggal

    The GHC developers are happy to announce the availability of GHC 9.4.5. This release is primarily a bugfix release addressing a few issues found in 9.4.4.

  • concurrency and Performance by Nicolas Trangez

    Testing concurrent code using DejaFu requires the use of MonadConc and MonadSTM instead of plain IO and STM. Is there any performance impact, and if there is, can it be recovered?

  • crem: Compositional Representable Executable Machines by Marco Perone

    I’d like to present crem, a new Haskell library to build state machines, and explain why Haskell plays an important role in making crem special.

  • falsify: Hypothesis-inspired shrinking for Haskell by Edsko de Vries

    In this blog post we will introduce falsify, a new library that provides property based testing in Haskell and has an approach to shrinking that is inspired by Hypothesis. As we shall see, however, the details are quite different.

  • Haskell/GHC refuses to compile ugly code by Dmitrii Kovanikov

    Recently, I experienced an unusual challenge when upgrading a 60K LOC Haskell project from GHC version 9.0 to 9.2, and I’d like to share my investigation journey and how I eventually fixed the problem.

  • How to create a bar chart from a CSV file with Haskell by Adrian Sieber

    I decided to use Haskell, but I couldn’t find any good code examples out there. So, I went ahead and wrote the code from scratch. I’m sharing it here in hopes of sparing the next person the time and effort.

  • IOSim on Hackage! by Marcin Szamotulski

    These packages support our goal of using the same code to run in production and simulation, what greatly increases the reliability and quality of the final system.

  • This is How to Build Haskell with GNU Make (and why it’s worth trying) by Monday Morning Haskell

    I wanted to structure my source code the same way I would in a Cabal-style application, but rely on GNU Make to chain together the necessary GHC compilation commands.


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In brief

Show & tell

  • Fourmolu version 0.12 by Brandon Chinn

    Fourmolu is a formatter for Haskell source code. It is a fork of Ormolu, with upstream improvements continually merged.

  • hlint-scan by Yoo Chung

    This is a GitHub action which scans Haskell code using HLint and uploads its suggested improvements to GitHub code scanning.

  • safe-gen by Jonas Carpay

    Writing Arbitrary instances is for recursive data is annoying, since it’s easy to accidentally write non-terminating generators.

  • SBV version 10.1 by Levent Erkok

    A new release of SBV is now on hackage, supporting quantifiers, quantifier alternation, quantifier elimination, and skolemization.

  • vector-quicksort by Sergey Vinokurov

    This package features reasonable sort function that is a good default for sorting mutable vectors using well-known quicksort algorithm.

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